historic region of southwestern Asia that is only roughly coterminous with modern Iran. The term Persia was used for centuries, chiefly in the West, to designate those regions where Persian language and culture predominated, but it more correctly refers to a region of southern Iran formerly known as Persis, alternatively as Pārs or Parsa, modern Fārs. Parsa was the name of an Indo-European nomadic people who migrated into the region about 1000 BC. The first mention of Parsa occurs in the annals of Shalmanesar II, an Assyrian king, in 844 BC. During the rule of the Persian Achaemenian dynasty (559–330 BC), the ancient Greeks first encountered the inhabitants of Persis on the Iranian plateau, when the Achaemenids—natives of Persis—were expanding their political sphere. The Achaemenids were the dominant dynasty during Greek history until the time of Alexander the Great, and the use of the name Persia was gradually extended by the Greeks and other peoples to apply to the whole Iranian plateau. This tendency was reinforced with the rise of the Sāsānian dynasty, also native to Persis, whose culture dominated the Iranian plateau until the 7th century AD. The people of this area have traditionally referred to the region as Iran, “Land of the Aryans,” and in 1935 the government of Iran requested that the name Iran be used in lieu of Persia. The two terms, however, are often used interchangeably when referring to periods preceding the 20th century.

This article covers the history of Iran and the Iranian peoples from the prehistoric period up to the Arab conquest in the 7th century AD. For the history of the succeeding periods, see the article Iran. For a discussion of the religions of ancient Iran, see Iranian religion. For a discussion of visual arts from the prehistoric period through the Sāsānian period, see art and architecture, Iranian. For a detailed account of Mesopotamian history through the Sāsānian period, see Mesopotamia, history of.

The early history of Iran may be divided into three phases: (1) the prehistoric period, beginning with the earliest evidence of humans on the Iranian plateau (c. 100,000 BC) and ending roughly at the start of the 1st millennium BC, (2) the protohistoric period, covering approximately the first half of the 1st millennium BC, and (3) the period of the Achaemenian dynasty (6th to 4th century BC), when Iran entered the full light of written history. The civilization of Elam, centred off the plateau in lowland Khūzestān, is an exception, for written history began there as early as it did in neighbouring Mesopotamia (c. 3000 BC).

The sources for the prehistoric period are entirely archaeological. Early excavation in Iran was limited to a few sites. In the 1930s archaeological exploration increased, but work was abruptly halted by the outbreak of World War II. After the war ended, interest in Iranian archaeology revived quickly, and, from 1950 until archaeological study was dramatically curtailed after 1979, numerous excavations revolutionized the study of prehistoric Iran.

For the protohistoric period the historian is still forced to rely primarily on archaeological evidence, but much information comes from written sources as well. None of these sources, however, is both local and contemporary in relation to the events described. Some sources are contemporary but belong to neighbouring civilizations that were only tangentially involved in events in the Iranian plateau—for example, the Assyrian and Babylonian cuneiform records from lowland Mesopotamia. Some are local but not contemporary, such as the traditional Iranian legends and tales that supposedly speak of events in the early 1st millennium BC. And some are neither contemporary nor local but are nevertheless valuable in reconstructing events in the protohistoric period (e.g., the 5th-century-BC Greek historian Herodotus).

For the study of the centuries of the Achaemenian dynasty, there is sufficient documentary material so that this period is the earliest for which archaeology is not the primary source of data. Contributing to the understanding of the period are, among other sources, economic texts from Mesopotamia, Elam, and Iran; historical inscriptions such as that of Darius I (the Great) at Behistun (modern Bīsotūn (Bīsitūn)); contemporary and later classical authors; and later Iranian legends and literature.

Enigmatic evidence of human presence on the Iranian plateau as early as Lower Paleolithic times comes from a surface find in the Bākhtarān valley. The first well-documented evidence of human habitation is in deposits from several excavated cave and rock-shelter sites, located mainly in the Zagros Mountains of western Iran and dated to Middle Paleolithic or Mousterian times (c. 100,000 BC). There is every reason to assume, however, that future excavations will reveal Lower Paleolithic habitation in Iran. The Mousterian (Mousterian industry) flint tool industry found there is generally characterized by an absence of the Levalloisian technique of chipping flint and thus differs from the well-defined Middle Paleolithic industries known elsewhere in the Middle East. The economic and social level associated with this industry is that of fairly small, peripatetic hunting and gathering groups spread out over a thinly settled landscape.

Locally, the Mousterian is followed by an Upper Paleolithic flint industry called the Baradostian. Radiocarbon dates suggest that this is one of the earliest Upper Paleolithic complexes; it may have begun as early as 36,000 BC. Its relationship to neighbouring industries, however, remains unclear. Possibly, after some cultural and typological discontinuity, perhaps caused by the maximum cold of the last phase of the Würm glaciation, the Baradostian was replaced by a local Upper Paleolithic industry called the Zarzian. This tool tradition, probably dating to the period 12,000 to 10,000 BC, marks the end of the Iranian Paleolithic sequence.

Evidence indicates that the Middle East in general was one of the earliest areas in the Old World to experience what the Australian archaeologist V. Gordon Childe called the Neolithic revolution. That revolution witnessed the development of settled village agricultural life based firmly on the domestication of plants and animals. Iran has yielded much evidence on the history of these important developments. From the early Neolithic Period (sometimes called the Mesolithic, or Middle Stone Age) comes evidence of significant shifts in tool manufacture, settlement patterns, and subsistence methods, including the fumbling beginnings of domestication of both plants and animals, at such western Iranian sites as Āsīāb, Gūrān, Ganj Dareh (Ganj Darreh), and Ali Kosh. Similar developments in the Zagros Mountains, on the Iraqi side of the modern border, are also traceable at sites such as Karīm Shahīr and Zawi Chemi–Shanidar. This phase of early experimentation with sedentary life and domestication was soon followed by a period of fully developed village farming as defined at important Zagros sites such as Jarmo, Sarāb, upper Ali Kosh, and upper Gūrān. All these sites date wholly or in part to the 8th and 7th millennia BC.

By approximately 6000 BC these patterns of village farming were widely spread over much of the Iranian plateau and in lowland Khūzestān. Tepe Sabz in Khūzestān, Hajji Firuz in Azerbaijan, Godin Tepe VII in northeastern Lorestān, Tepe Sialk I on the rim of the central salt desert, and Tepe Yahya VI C–E in the southeast are all sites that have yielded evidence of fairly sophisticated patterns of agricultural (agriculture, origins of) life (Roman numerals identify the level of excavation). Though distinctly different, all show general cultural connections with the beginnings of settled village life in neighbouring areas such as Afghanistan, Baluchistan, Central Asia (Central Asia, history of), and Mesopotamia.

Rather less is known of the cultures in this time range in Iran than of contemporary cultures elsewhere in the ancient Middle East. Research has tended to concentrate on the Neolithic and protohistoric periods, and the scattered evidence for important cultural and artistic developments in the Chalcolithic Period (Copper Age) and Early Bronze Age resists coherent summary. It is clear that trends that began in the late Neolithic Period continued in the millennia that followed and that the rugged, broken landscape of the Iranian plateau forced people into a variety of relatively isolated cultures. In no instance, with the important exception of Elam (see The Elamites (Iran, ancient), below), did Iran participate in the developments that led to fully urban civilization in lowland Mesopotamia to the west or in the Indus valley to the east. Throughout prehistory the Iranian plateau remained at the economic and cultural level of village life achieved in the Neolithic Period. The separate cultural areas on the plateau are as yet barely understood by the modern archaeologist in any terms other than through the painted pottery assemblages found at several sites throughout Iran. Though they developed in comparative isolation, each of these areas does yield some evidence of cultural contact with its immediate neighbours and, in some striking cases, with developments in the centres of higher civilization in Mesopotamia. Trade would appear to be the principal mechanism by which such contacts were maintained, and often Elam appears to have acted as an intermediary between Sumer and Babylon on the one hand and the plateau cultures on the other. Trade across the northern part of the plateau, through the sites of Tepe Hissar and Sialk, most probably involved transshipping semiprecious stones such as lapis lazuli from Afghanistan to Mesopotamia. The appearance of proto-Elamite tablets in Sialk IV may bear witness to such trade. So also may the appearance of similar proto-Elamite tablets at Tepe Yahya south of Kermān and in the great central desert provide evidence of trade connections between Mesopotamia and the east—in this case a trade that may have centred on specific items such as steatite and copper. Parsa perhaps also participated in such trade networks, as is suggested by the appearance there, alongside strictly local ceramics, of wares that have clear Mesopotamian affinities. In the west-central Zagros, outside influences from both the north and the west can be traced in the ceramic record; such is also the case for local cultures in Azerbaijan to the northwest. In general, however, these millennia represent a major dark age in Iranian prehistory and warrant considerably more attention than they have received.

The beginning of this period is generally characterized by an even more marked isolation of the plateau than earlier, while the latter half of the period is one of major new disruptions, heretofore unique in Iranian history, that laid the groundwork for developments in the protohistoric period. In northwestern and central western Iran, local cultures, as yet barely defined beyond their ceramic parameters, developed in relative isolation from events elsewhere. All occupation had ceased at Tepe Sialk, but the painted pottery cultures characteristic of earlier Hissar and of the sites in the Gorgān lowland in the northeast continued. Little Mesopotamian influence is evident, though some contacts between Elam and the plateau remained. Beginning perhaps as early as 2400 BC but more probably somewhat later, a radical transformation occurred in the culture of the northeast: earlier painted potteries were entirely replaced by a distinctive gray or gray-black ceramic associated with a variety of other artifacts, primarily weapons and ornaments in copper or bronze, which were also unique. Whether this cultural change represents a strictly local development or testifies to an important intrusion of new peoples into the area is still under debate. In any case, none of these developments can be traced to Mesopotamia or to other areas to the west, regions which had previously been the sources of outside influences on the Iranian plateau. Somewhat later the local cultures of central and northwestern Iran were apparently influenced by developments in northern Mesopotamia and Assyria, along patterns of contact that had been well established in earlier periods. Yet this contact, as it is observed at Godin III, Hasanlu VI, and Dinkha Tepe, did not cause any major dislocation of local cultural patterns. In the second half of the 2nd millennium, however, western Iran—at first perhaps gradually and then with striking suddenness—came under the influence of the gray and gray-black ware cultures that had developed earlier in the northeast. There the impact of these influences was such as to definitely suggest a major cultural dislocation and the introduction of a whole new culture—and probably a new people—into the Zagros. It was this development that marked the end of the Bronze Age in western Iran and ushered in the early protohistoric period.

Whereas the Iranian plateau did not experience the rise of urban, literate civilization in the late 4th and early 3rd millennia on the Mesopotamian pattern, lowland Khūzestān did. There Elamite civilization was centred. Geographically, Elam included more than Khūzestān; it was a combination of the lowlands and the immediate highland areas to the north and east. Elamite strength was based on an ability to hold these various areas together under a coordinated government that permitted the maximum interchange of the natural resources unique to each region. Traditionally this was done through a federated governmental structure.

Closely related to that form of government was the Elamite system of inheritance and power distribution. The normal pattern of government was that of an overlord ruling over vassal princes. In earliest times the overlord lived in Susa, which functioned as a federal capital. With him ruled his brother closest in age, the viceroy, who usually had his seat of government in the native city of the currently ruling dynasty. This viceroy was heir presumptive to the overlord. Yet a third official, the regent or prince of Susa (the district), shared power with the overlord and the viceroy. He was usually the overlord's son or, if no son was available, his nephew. On the death of the overlord, the viceroy became overlord. The prince of Susa remained in office, and the brother of the old viceroy nearest to him in age became the new viceroy. Only if all brothers were dead was the prince of Susa promoted to viceroy, thus enabling the overlord to name his own son (or nephew) as the new prince of Susa. Such a complicated system of governmental checks, balances, and power inheritance often broke down, despite bilateral descent and levirate marriage (the compulsory marriage of a widow to her deceased husband's brother). What is remarkable is how often the system did work; it was only in the Middle and Neo-Elamite periods that sons more often succeeded fathers to power.

Elamite history can be divided into three main phases: the Old, Middle, and Late, or Neo-Elamite, periods. In all periods Elam was closely involved with Sumer, Babylonia, and Assyria, sometimes through peaceful trade but more often through war. In like manner, Elam was often a participant in events on the Iranian plateau. Both involvements were related to the combined need of all the lowland civilizations to control the warlike peoples to the east and to exploit the economic resources of the plateau.

The earliest kings in the Old Elamite period may date to approximately 2700 BC. Already conflict with Mesopotamia, in this case apparently with the city of Ur, was characteristic of Elamite history. These early rulers were succeeded by the Awan (Shūstar) dynasty. The 11th king of this line entered into treaty relations with the great Naram-Sin of Akkad (reigned c. 254–c. 2218 BC). Yet a new ruling house soon appeared, the Simash dynasty (Simash may have been in the mountains of southern Lorestān). The outstanding event of this period was the virtual conquest of Elam by Shulgi of the 3rd dynasty of Ur (c. 2094–c. 2047 BC). Eventually the Elamites rose in rebellion and overthrew the 3rd Ur dynasty, an event long remembered in Mesopotamian dirges and omen texts. About the mid 19th century BC, power in Elam passed to a new dynasty, that of Eparti. The third king of this line, Shirukdukh, was active in various military coalitions against the rising power of Babylon (Babylonia), but Hammurabi was not to be denied, and Elam was crushed in 1764 BC. The Old Babylon kingdom, however, fell into rapid decline following the death of Hammurabi, and it was not long before the Elamites were able to gain revenge. Kutir-Nahhunte I attacked Samsuiluna (c. 1749–c. 1712 BC), Hammurabi's son, and dealt so serious a defeat to the Babylonians that the event was remembered more than 1,000 years later in an inscription of the Assyrian king Ashurbanipal. It may be assumed that with this stroke Elam once again gained independence. The end of the Eparti dynasty, which occurred possibly in the late 16th century BC, is buried in silence.

After two centuries for which sources reveal nothing, the Middle Elamite period opened with the rise to power of the Anzanite dynasty, whose homeland probably lay in the mountains northeast of modern Khūzestān. Political expansion under Khumbannumena (c. 1285–c. 1266 BC), the fourth king of this line, proceeded apace, and his successes were commemorated by his assumption of the title “Expander of the Empire.” He was succeeded by his son, Untash-Gal (Untash 【d】 Gal, or Untash-Huban), a contemporary of Shalmaneser I of Assyria (c. 1274–c. 1245 BC) and the founder of the city of Dūr Untash (modern Choghā Zanbīl). In the years immediately following Untash-Gal's reign, Elam increasingly found itself in real or potential conflict with the rising power of Assyria. Tukulti-Ninurta I of Assyria campaigned in the mountains north of Elam in the latter part of the 13th century BC. The Elamites under Kidin-Khutran, the second king after Untash-Gal, countered with a successful and devastating raid on Babylonia. In the end, however, Assyrian power seems to have been too great. Tukulti-Ninurta managed to expand, for a brief time, Assyrian control well to the south in Mesopotamia. Kidin-Khutran faded into obscurity, and the Anzanite dynasty came to an end.

After a short period of dynastic troubles, the second half of the Middle Elamite period opened with the reign of Shutruk-Nahhunte I (c. 1160 BC). Two equally powerful and two rather less impressive kings followed this founder of a new dynasty, whose home was probably Susa, and in this period Elam became one of the great military powers of the Middle East. Tukulti-Ninurta died about 1208 BC, and Assyria fell into a period of internal weakness and dynastic conflict. Elam was quick to take advantage of this situation by campaigning extensively in the Diyālā River area and into the very heart of Mesopotamia. Shutruk-Nahhunte I captured Babylon and carried off to Susa the stela on which was inscribed the famous law code of Hammurabi. Shilkhak-In-Shushinak, brother and successor of Shutruk-Nahhunte's eldest son, Kutir-Nahhunte, still anxious to take advantage of Assyrian weakness, campaigned as far north as the area of modern Kirkūk. In Babylonia, however, the 2nd dynasty of Isin led a native revolt against such control as the Elamites had been able to exercise there, and Elamite power in central Mesopotamia was eventually broken. The Elamite military empire began to shrink rapidly. Nebuchadrezzar I of Babylon (c. 1119–c. 1098 BC) attacked Elam and was just barely thwarted. A second Babylonian attack succeeded, however, and the whole of Elam was apparently overrun, ending the Middle Elamite period.

It is noteworthy that during the Middle Elamite period the old system of succession to, and distribution of, power appears to have broken down. Increasingly, son succeeded father, and less is heard of divided authority within a federated system. This probably reflects an effort to increase the central authority at Susa in order to conduct effective military campaigns abroad and to hold Elamite foreign conquests. The old system of regionalism balanced with federalism must have suffered, and the fraternal, sectional strife that so weakened Elam in the Neo-Elamite period may have had its roots in the centrifugal developments of the 13th and 12th centuries BC.

A long period of darkness separates the Middle and Neo-Elamite periods. In 742 BC a certain Huban-Nugash is mentioned as king in Elam. The land appears to have been divided into separate principalities, with the central power fairly weak. During the next century the Elamites constantly attempted to interfere in Mesopotamian affairs, usually in alliance with Babylon, against the constant pressure of Neo-Assyrian expansion. At times they were successful with this policy, both militarily and diplomatically, but on the whole they were forced to give way to increasing Assyrian power. Local Elamite dynastic troubles were from time to time compounded by both Assyrian and Babylonian interference. Meanwhile the Assyrian army whittled away at Elamite power and influence in Luristan. In time these internal and external pressures produced a near total collapse of any meaningful central authority in Elam. In an effort to clean up a political and diplomatic mess that had become a chronic headache for the Assyrians, Ashurbanipal's armies mounted a series of campaigns between 692 and 639 BC that utterly destroyed Susa, pulling down buildings, looting, and sowing the land of Elam with salt.

The beginning of the Iron Age is marked by major dislocations of cultural and historical patterns in western Iran (almost nothing is known of the eastern half of the plateau in the Iron Age). The Iron Age itself is divided into three periods: Iron Age I (c. 1300–c. 1000 BC), Iron Age II (c. 1000–c. 800/750 BC), and Iron Age III (c. 750–c. 550 BC). The latter is the archaeological equivalent of what historically can be called the Median period.

Though isolated groups of speakers of Indo-European languages had appeared and disappeared in western Iran in the 2nd millennium BC, it was during the Iron Age that the Indo-European Iranians rose to be the dominant force on the plateau. By the mid-9th century BC two major groups of Iranians appeared in cuneiform sources: the Medes (Mede) and the Persians. Of the two the Medes were the more widespread and, from an Assyrian (Assyria) point of view, the more important group. When Assyrian armies raided as far east as modern Hamadān, they found only Medes. In the more western Zagros (Zagros Mountains) they encountered Medes mixed with non-Iranian indigenous peoples. Early in the 1st millennium Iranian Medes already controlled almost all of the eastern Zagros and were infiltrating, if not actually pushing steadily into, the western Zagros, in some areas right up to the edge of the plateau and to the borders of lowland Mesopotamia. Persians also appear in roughly the same areas, though their exact location remains controversial. At times they seem to have settled in the north near Lake Urmia, at times in the central western Zagros near modern Kermānshāh, later certainly in the southwestern Zagros somewhere near the borders of Elam, and eventually, of course, in the region of Fārs. It has been argued that these various locations represent a nomadic tribe on the move; more likely they represent more than one group of Persians. What is reasonably clear from the cuneiform sources is that these Medes and Persians (and no doubt other Iranian peoples not identified by name) were moving into western Iran from the east. They probably followed routes along the southern face of the Elburz Mountains and, as they entered the Zagros, spread out to the northwest and southeast following the natural topography of the mountains. Where they could, they infiltrated farther west—for example, along the major pass across the mountains from Hamadān to Kermānshāh. In doing so, they met resistance from the local settled populations, who often appealed to Urartu, Assyria, and Elam for assistance in holding back the newcomers. Such appeals were, of course, most welcome to these great powers, who were willing to take advantage of the situation both to advance their interests at each other's expense and to control the Iranian threat to themselves.

It has been suggested that the introduction of gray and gray-black pottery into western Iran from the northeast, which signals the start of the Iron Age, is the archaeological manifestation of this pattern of a gradual movement of Iranians from east to west. The case is by no means proved, but it is a reasonable reading of the combined evidence. If it is so, then the earliest Iranians in the Zagros Mountains can be dated to Iron Age I times, about 1300 BC. Archaeologically, the culture of Iron Age II times can be seen as having evolved out of that of the Iron Age I period, and, though the development is less clear, the same can be said of the relationship between the cultures of Iron Age II and III. The spread of the Iron Age I and II cultures in the Zagros is restricted and would appear to correspond fairly well with the distribution of Iranians known from the written documents. The distribution of the Iron Age III culture, on the other hand, is, at least by the 7th century BC, much more widespread and covers almost the whole of the Zagros. Thus, the argument that links these archaeological patterns with the Iranian migration into the area associates the Iron Age I and II cultures with the early penetration of the Iranians into the more eastern Zagros and with their infiltration westward along the major routes crosscutting the main mountain alignments. Those areas where traces of the Iron Age I and II cultures do not appear were the regions still under the control of non-Iranian indigenous groups supported by Urartu, Assyria, and Elam. The widespread Iron Age III culture is then associated with the rise to power of the Median kingdom in the 7th and early 6th centuries BC and the Iranianization of the whole of the Zagros Mountains.

Traditionally, the creator of the Median kingdom was one Deioces, who, according to Herodotus, reigned from 728 to 675 BC and founded the Median capital Ecbatana (modern Hamadān). Attempts have been made to associate Dāiukku, a local Zagros king mentioned in a cuneiform text as one of the captives deported to Assyria by Sargon II in 714 BC, with the Deioces of Herodotus, but such an association is highly unlikely. To judge from the Assyrian sources, no Median kingdom such as Herodotus describes for the reign of Deioces existed in the early 7th century BC; at best, he is reporting a Median legend of the founding of their kingdom.

According to Herodotus, Deioces was succeeded by his son Phraortes (reigned 675–653 BC), who subjugated the Persians and lost his life in a premature attack against the Assyrians. Some of this tale may be true. Assyrian texts speak of a Kashtariti as the leader of a conglomerate group of Medes, Scythians (Scythian), Mannaeans, and miscellaneous other local Zagros peoples that seriously threatened the peace of Assyria's eastern borderlands during the reign of Esarhaddon (680–669 BC). It is possible that Phraortes is this Kashtariti, though the suggestion cannot be proved either historically or linguistically. That a Median king in this period exerted political and military control over the Persians is entirely reasonable, though it cannot be proved.

Beginning as early as the 9th century BC and with increasing impact in the late 8th and early 7th centuries, groups of nomadic warriors entered western Iran, probably from across the Caucasus. Dominant among these groups were the Scythians, and their entrance into the affairs of the western plateau during the 7th century may perhaps mark one of the turning points in Iron Age history. Herodotus speaks in some detail of a period of Scythian domination, the so-called Scythian interregnum in Median dynasty history. His dating of this event remains uncertain, but traditionally it is seen as falling between the reigns of Phraortes and Cyaxares and covering the years 653 to 625 BC. Whether such an interregnum ever actually occurred and, if it did, whether it should not be dated later than this are open questions. What is clear is that by the mid 7th century BC there were a great many Scythians in western Iran, that they—along with the Medes and other groups—posed a serious threat to Assyria, and that their appearance threw previous power alignments quite out of balance.

Herodotus reports how, under Cyaxares of Media (625–585 BC), the Scythians were overthrown when their kings were induced at a supper party to get so drunk that they were then easily slain. It is more likely that about this time either the Scythians withdrew voluntarily from western Iran and went off to plunder elsewhere or they were simply absorbed into a rapidly developing confederation under Median hegemony. Cyaxares is a fully historical figure who appears in the cuneiform sources as Uvakhshatra. Herodotus speaks of how Cyaxares reorganized the Median army into units built around specialized armaments: spearmen, archers, and cavalry. The unified and reorganized Medes were a match for the Assyrians. They attacked one of the important Assyrian border cities, Arrapkha (Kirkūk), in 615 BC, surrounded Nineveh in 614 but were unable to capture it, and instead successfully stormed the Assyrian religious capital, Ashur. An alliance between Babylon (Babylonia) and the Medes was sealed by the betrothal of Cyaxares' granddaughter to Babylonian King Nabopolassar's son, Nebuchadrezzar II (605–562 BC). In 612 the attack on Nineveh was renewed, and the city fell in late August (the Babylonians arrived rather too late to participate fully in the battle). The Babylonians and the Medes together pursued the fleeing Assyrians westward into Syria. Assyrian appeals to Egypt for help came to naught, and the last Assyrian ruler, Ashur-uballiṭ II, disappeared from history in 609.

The problem, of course, was how to divide the spoils among the victors. The cuneiform sources are comparatively silent, but it would seem that the Babylonians fell heir to all of the Assyrian holdings within the Fertile Crescent, while their allies took over all of the highland areas. The Medes gained control over the lands in eastern Anatolia that had once been part of Urartu and eventually became embroiled in war with the Lydians, the dominant political power in western Asia Minor. In 585 BC, probably through the mediation of the Babylonians, peace was established between Media and Lydia, and the Halys (Kızıl) River was fixed as the boundary between the two kingdoms. Thus a new balance of power was established in the Middle East among Medes, Lydians, Babylonians, and, far to the south, Egyptians. At his death Cyaxares controlled vast territories: all of Anatolia to the Halys; the whole of western Iran eastward, perhaps as far as the area of modern Tehrān; and all of southwestern Iran, including Fārs. Whether it is appropriate to call these holdings a kingdom is debatable; one suspects that authority over the various peoples, Iranian and non-Iranian, who occupied these territories was exerted in the form of a confederation such as is implied by the ancient Iranian royal title, king of kings.

The ruling dynasty of the Persians that was settled in Fārs in southwestern Iran (possibly the Parsumash of the later Assyrian records) traced its ancestry back to an eponymous ancestor, Hāxamanish, or Achaemenes. There is no historical evidence of such a king's existence. Traditionally, three rulers fell between Achaemenes and Cyrus II: Teispes, Cyrus I, and Cambyses I. Teispes, freed of Median domination during the so-called Scythian interregnum, is thought to have expanded his kingdom and to have divided it on his death between his two sons, Cyrus I and Ariaramnes. Cyrus I may have been the king of Persia who appears in the records of Ashurbanipal swearing allegiance to Assyria after the devastation of Elam in the campaigns of 642–639 BC, though there are chronological problems involved with this equation. When Median control over the Persians was supposedly reasserted under Cyaxares, Cambyses I is thought to have been given a reunited Persia to administer as a Median vassal. His son, Cyrus II, married the daughter of Astyages and in 559 inherited his father's position within the Median confederation.

Cyrus II certainly warranted his later title, Cyrus the Great. He must have been a remarkable personality, and certainly he was a remarkable king. He united under his authority several Persian and Iranian groups who apparently had not been under his father's control. He then initiated diplomatic exchanges with Nabonidus of Babylon (556–539 BC), which justifiably worried Astyages. Eventually he openly rebelled against the Medes, who were beaten in battle when considerable numbers of Median troops deserted to the Persian standard. Thus in 550 the Median empire became the first Persian empire, and the Achaemenian kings appeared on the international scene with a suddenness that must have frightened many.

Cyrus immediately set out to expand his conquests. After apparently convincing the Babylonians (Babylon) that they had nothing to fear from Persia, he turned against the Lydians under the rule of the fabulously wealthy Croesus. Lydian appeals to Babylon were to no avail. He then took Cilicia, thus cutting the routes over which any help might have reached the Lydians. Croesus attacked, and an indecisive battle was fought in 547 BC on the Halys River. Since it was late in the campaigning season, the Lydians thought the war was over for that year, returned to their capital at Sardis, and dispersed the national levy. Cyrus, however, kept coming. He caught and besieged the Lydians in the citadel at Sardis and captured Croesus in 546. Of the Greek city-states along the western coast of Asia Minor, heretofore under Lydian control, only Miletus surrendered without a fight. The others were systematically reduced by the Persian armies led by subordinate generals. Cyrus himself was apparently busy elsewhere, possibly in the east, for little is known of his activities between the capture of Sardis and the beginning of the Babylonian campaign in 540.

Nowhere did Cyrus display his political and military genius better than in the conquest of Babylon. The campaign actually began when he lulled the Babylonians into inactivity during his war with Lydia, which, since it was carried to a successful conclusion, deprived the Babylonians of a potential ally when their turn came. Then he took full advantage of internal disaffection and discontent within Babylon. Nabonidus was not a popular king: he had paid too little attention to home affairs and had alienated the native Babylonian priesthood. The writer of Deutero-Isaiah, speaking for many of the captive Jews in Babylon, undoubtedly represented the hopes of many of Nabonidus's subjects that Cyrus was a potential deliverer. With the stage thus set, the military campaign against Babylon came almost as an anticlimax. The fall of the greatest city in the Middle East was swift; Cyrus marched into town in the late summer of 539 BC, seized the hands of the statue of the city god Marduk as a signal of his willingness to rule as a Babylonian and not as a foreign conqueror, and was hailed by many as the legitimate successor to the throne. In one stride Cyrus carried Persian power to the borders of Egypt, for with Babylon came all that it had seized from the Assyrians and gained in the sequel.

Little is known of the remainder of Cyrus's reign. The rapidity with which his son and successor, Cambyses II, initiated a successful campaign against Egypt suggests that preparations for such an attack were well advanced under Cyrus. But the founder of Persian power was forced to turn east late in his reign to protect that frontier against warlike tribes who were themselves in part Iranians and who threatened the plateau in the same manner as had the Medes and the Persians more than a millennium earlier. One of the recurrent themes of Iranian history is the threat of peoples from the east. How much Cyrus conquered in the east is uncertain. What is clear is that he lost his life in 529 BC, fighting somewhere in the region of the Oxus ( Amu Darya) and Jaxartes ( Syr Darya) rivers.

In 522 BC news reached Cambyses of a revolt in Iran led by an impostor claiming to be Bardiya, Cambyses' brother. Several provinces of the empire accepted the new ruler, who bribed his subjects by remitting taxes for three years. Cambyses died—possibly by his own hand but more probably from infection following an accidental sword wound—as he hastened home to regain control. Darius, a leading general in Cambyses' army and one of the princes of the Achaemenid family, raced homeward with the troops in order to crush the rebellion in a manner profitable to himself.

Cambyses has been rather mistreated in the sources, partly because of the prejudices of Herodotus's Egyptian informers and partly because of the propagandist motives of Darius I. Cambyses is reported to have ruled the Egyptians harshly and to have desecrated their religious ceremonies and shrines. His military campaigns out of Egypt were all reported as failures. He was accused of suicide in the face of revolt at home. It was even suggested that he was mad. There is, however, little solid contemporary evidence to support these charges.

Darius I, called the Great, tells in detail the story of the overthrow of the false Bardiya and of the first year of his own rule in his famous royal inscription cut on a rock face at the base of Mount Bīsotūn, a few miles east of modern Kermānshāh. Some historians consider Darius's account to be mere propaganda and argue instead that Bardiya was not an imposter. According to Darius, six leading Achaemenian nobles assisted in slaying the imposter and together proclaimed Darius the rightful heir of Cambyses. Darius was a member of the Achaemenian royal house. His great-grandfather was Ariaramnes, son of Teispes, who had shared power in Persia with his brother Cyrus I. Ariaramnes' son, Arsames, and his grandson, Hystaspes (Darius's father), had not been kings in Persia, as unified royal power had been placed in the hands of Cambyses I by Cyaxares. Neither is named a king in Darius's own inscriptions. Hystaspes was, however, an important royal prince and apparently the governor of Persis. Darius himself was in the mold of Cyrus the Great—a powerful personality and a dynamic ruler.

It took more than a year (522–521 BC) of hard fighting to put down the revolts associated with Bardiya's claim to the throne and Darius's succession to power. Almost every province of the empire was involved in the conflict, including Persia and, most particularly, Media. A balanced policy of clemency backed by the swift and thorough punishment of any captured rebel leader, in combination with a well-coordinated and carefully timed distribution of loyal forces, eventually brought peace to the empire and undisputed power to Darius. He then turned his attention to the organization and consolidation of his inheritance, and it was for this role—that of lawgiver and organizer—that he himself, to judge from his inscriptions, most wished to be remembered.

Such activities, however, did not prevent Darius from following an active expansionist policy. Campaigns to the east confirmed gains probably made by Cyrus the Great and added large sections of the northern Indian subcontinent to the list of Persian-controlled provinces. Expansion in the west began about 516 BC when Darius moved against the Hellespont as a first step toward an attack on the Scythians along the western and northern shores of the Black Sea. The real strategic purpose behind this move probably was to disrupt and, if possible, interrupt Greek trade with the Black Sea area, which supplied much grain to Greece. Crossing into Europe for the first time, Darius campaigned with comparatively little success to the north of the Danube River. He retreated in good order, however, with only limited losses, and a bridgehead across the Hellespont was established.

Perhaps partly in response to these developments or perhaps for more purely internal reasons, the Ionian Greek cities on the west coast of Asia Minor revolted against Persian rule in 500 BC. The Persians were apparently taken by surprise, and at first the rebellion prospered. The Ionians received some limited assistance from the Athenians (Athens) and in 498 felt strong enough to make another offensive. With one hand Darius negotiated; with the other he assembled a counterattack. The first Persian military efforts proved only partially successful, however, and the Ionians enjoyed another respite in the years 496–495. A renewed Persian offensive in 494 was successful. The Greek fleet was badly beaten off Miletus, and the Persian land army began a systematic reduction of the rebel cities. About 492 Mardonius, a son-in-law of Darius, was made special commissioner to Ionia. He suppressed local tyrants and returned democratic government to many cities. In time the wounds caused by the revolt and its suppression healed, and by 481 Xerxes (Xerxes I) was able to levy troops in this region with little trouble.

By 492 BC Mardonius had also recovered Persian Thrace and Macedonia, first gained in the campaign against the Scythians and lost during the Ionian revolt. There followed the Persian invasion of Greece (Greco-Persian Wars) that led to Darius's defeat at the Battle of Marathon (Marathon, Battle of) late in the summer of 490 BC. The great king was forced to retreat and to face the fact that the Greek problem, which had probably seemed to the Persians a minor issue on the western extremity of the empire, would require a more concerted and massive effort. Thus began preparations for an invasion of Greece on a grand, coordinated scale. These plans were interrupted in 486 by two events: a serious revolt in Egypt, and the death of Darius.

Xerxes (reigned 486–465 BC), Darius's eldest son by Queen Atossa, was born after his father had come to the throne; he had been designated official heir perhaps as early as 498, and while crown prince he had ruled as the king's governor in Babylon. The new king quickly suppressed the revolt in Egypt in a single campaign in 484. Xerxes then broke with the policy followed by Cyrus and Darius of ruling foreign lands with a fairly light hand, and, in a manner compatible with local traditions, he ruthlessly ignored Egyptian forms of rule and imposed his will on the rebellious province in a thoroughly Persian style. Plans for the invasion of Greece begun under Darius were then still further delayed by a major revolt in Babylonia about 482 BC, which also was suppressed with a heavy hand.

Xerxes then turned his attention westward to Greece. He wintered in Sardis in 481–480 and thence led a combined land and sea invasion of Greece. Northern Greece fell to the invaders in the summer of 480, the Greek stand at Thermopylae in August of 480 came to naught, and the Persian land forces marched on Athens, taking and burning the Acropolis. But the Persian fleet lost the Battle of Salamis (Salamis, Battle of), and the impetus of the invasion was blunted. Xerxes, who had by then been away from Asia rather long for a king with such widespread responsibilities, returned home and left Mardonius in charge of further operations. The real end of the invasion came with the Battle of Plataea, the fall of Thebes (a stronghold of pro-Persian forces), and the Persian naval loss at Mycale in 479. Of the three, the Persian loss at Plataea was perhaps the most decisive. Up until Mardonius was killed, the issue of the battle was probably still in doubt, but, once leaderless, the less organized and less disciplined Persian forces collapsed. Time and again in later years this was to be the pattern in such encounters, for the Persians never solved the military problem posed by the disciplined Greek hoplites.

The formation of the Delian League, the rise of Athenian imperialism, troubles on the west coast of Asia Minor, and the end of Persian military ambitions in the Aegean followed rapidly in the decade after Plataea. Xerxes probably lost interest in the proceedings and sank deeper and deeper into the comforts of life in his capital cities of Susa, Ecbatana, and Persepolis. Harem intrigues, which were steadily to sap the strength and vitality of the Achaemenian Empire, led to the king's assassination in 465 BC.

The death of Xerxes was a major turning point in Achaemenian history. Occasional flashes of vigour and intelligence by some of Xerxes' successors were too infrequent to prevent eventual collapse but did allow the empire to die gradually. It is a tribute to Cyrus, Cambyses, and Darius that the empire they constructed was as resilient as it proved to be after Xerxes.

The three kings that followed Xerxes on the throne— Artaxerxes I (reigned 465–425 BC), Xerxes II (425–424), and Darius II Ochus (423–404)—were all comparatively weak as individuals and as kings, and such successes as the empire enjoyed during their reigns were mainly the result of the efforts of subordinates or of the troubles faced by their adversaries. Artaxerxes I faced several rebellions, the most important of which was that of Egypt in 459, not fully suppressed until 454. An advantageous peace (the Peace of Callias) with Athens was signed in 448 BC, whereby the Persians agreed to stay out of the Aegean and the Athenians agreed to leave Asia Minor to the Achaemenids. Athens broke the peace in 439 in an attack on Samos, and in its aftermath the Persians made some military gains in the west. Xerxes II ruled only about 45 days and was killed while in a drunken stupor by the son of one of his father's concubines. The assassin was himself killed by Darius II, who rose to the throne through palace intrigue. Several revolts marred his reign, including one in Media, which was rather close to home.

The major event of these three reigns was the Peloponnesian War between Sparta and Athens, which was fought, with occasional pauses, over the latter decades of the 5th century BC. The situation was ripe for exploitation by the famous “Persian archers,” the gold coins of the Achaemenids that depicted an archer on their obverse and that were used with considerable skill by the Persians in bribing first one Greek state and then another. Initially the Persians encouraged Athens against Sparta and from this gained the Peace of Callias. Then, after the disastrous Athenian campaign against Sicily in 413, the Persians intervened on Sparta's side. By the treaty of Miletus in 412, the Persians recovered complete freedom in western Asia Minor in return for agreeing to pay for seamen to man the Peloponnesian fleet. Persian gold and Spartan soldiers brought about the fall of Athens in 404 BC. Despite the fact that the Persians played the two sides against each other to their own advantage, they should have done better. One observes a certain lack of control from Susa by the king in these proceedings, and the two principal governors in Asia Minor who were involved, Tissaphernes of Sardis and Pharnabazus of Hellespontine Phrygia, seemed to have permitted a personal power rivalry to stand in the way of a really coordinated Persian intervention in the Greek war. When Egypt revolted in 405 BC, Persia was unable to do much about it, and from that point forward Egypt remained essentially an independent state.

Sparta, triumphant over Athens, built a small empire of its own and was soon involved in a war against the Persians, the principal issue again being the Greek cities of Asia Minor (Anatolia). While Sparta played one Persian governor in Anatolia against the other, the Persians spent gold in Greece to raise rebellion on Sparta's home ground. The Persians rebuilt their fleet and placed a competent Athenian admiral, Conon, in command. The contest continued from 400 to 387, with Sparta forced to act on an ever-shrinking front. A revitalized Athens, supported by Persia, created a balance of power in Greece, and eventually Artaxerxes was able to step in, at the Greeks' request, and dictate the so-called King's Peace of 387–386 BC. Once again the Greeks gave up any claim to Asia Minor and further agreed to maintain the status quo in Greece itself.

Cyrus the Younger, though caught in an assassination attempt at the time of Artaxerxes' coronation, was nevertheless forgiven and was returned to the command of a province in Asia Minor. But he revolted again in 401 BC and, supported by 10,000 Greek mercenaries, marched eastward to contest the throne. He was defeated and killed at the Battle of Cunaxa (Cunaxa, Battle of) in Mesopotamia that summer. The Greek mercenaries, however, were not broken and, though harried, left the field in good order and began their famous march, recorded in the Anabasis of Xenophon, north to the Black Sea and home. Probably no other event in late Achaemenian history revealed more clearly to the Greeks the essential internal weakness of the Achaemenian Empire than the escape of so large a body of men from the very heart of the Persian domain.

Since 379 BC Artaxerxes had been gathering Greek mercenaries in order to mount a campaign against Egypt. An attack in 373 failed against the native Egyptian 30th dynasty. On the heels of this failure came the revolt of the satraps, or provincial governors. Several satraps rose against the central power, and one, Aroandas (Orontes), a satrap of Armenia, went so far as to stamp his own gold coinage as a direct challenge to Artaxerxes. The general plan of the rebels appears to have been for a combined attack. The rebel satraps were to coordinate their march eastward through Syria with an Egyptian attack, under the king Tachos, and support by Greek mercenaries. The Egyptian attack was called off because of a revolt in Egypt by Tachos's brother, and Artaxerxes managed to defeat the satraps who were left alone to face the king's wrath. Several of the satraps, including Aroandas, were actually forgiven and returned to their governorships. In general the impression is that, in the end, rather than fight the central authority, the satraps were willing to return to their own provinces and plunder there in the name of Artaxerxes. Perhaps they saw that they actually had more authority and more control over real events in their own provincial territories than Artaxerxes had in his empire.

Plot and counterplot, harem intrigue, and murder brought Artaxerxes III to the throne in 359 BC. He promptly exterminated many of his relatives who might have challenged his rule—all to no avail, for revolts continued to rock the empire. A fresh attempt to win back Egypt was repulsed in 351. This setback encouraged revolt in Sidon and eventually in all of Palestine and Phoenicia. Parts of Cilicia joined the rebellion, but the revolt there was crushed in 345, the same year it had begun. Peace was achieved only temporarily; mercenaries from Thebes and the Argives, as well as from the Greek cities of Asia Minor, gathered for a new attempt on Egypt. Led by Artaxerxes III himself, it succeeded in 343 BC. But the local Egyptian dynasty fled south to Nubia, where it maintained an independent kingdom that kept alive the hopes of a dynastic revival. Persia then misplayed its hand in Greece by refusing aid to Athens against the rising power of Philip II of Macedon. In 339 BC Persian troops were fighting alone in Thrace against the Macedonians, and in the following year, at the Battle of Chaeronea, Philip extended his hegemony over all of Greece—a united Greece that was to prove impervious to Persian gold.

Artaxerxes was poisoned by his physician at the order of the eunuch Bagoas. The latter made Artaxerxes' youngest son, Arses, king (338–336 BC) in hopes of being the power behind the throne, but Arses did not bend easily to Bagoas's will. He attempted to poison the kingmaker but was himself killed in retaliation. Bagoas then engineered the accession of Darius III, a 45-year-old former satrap of Armenia. So many members of the royal house had been murdered in the court intrigue that Darius probably held the closest blood claim to the throne by virtue of being the grandnephew of Artaxerxes II. Darius was able to put down yet another rebellion in Egypt under Khababash in 337–336 BC, but the beginning of the end of the Achaemenian Empire came soon afterward, in May 334, when he lost the Battle of Granicus (Granicus, Battle of the) to Alexander the Great. Persepolis fell to the invader in April 330, and Darius, the last Achaemenid, was murdered in the summer of the same year while fleeing the conqueror. His unfinished tomb at Persepolis bears witness to his lack of preparation.

Alexander did not win his victories easily, however, and the catalog of troubles that marked the latter part of the Achaemenian Empire—rebellions, murders, weak kings trapped in the harems, missed chances, and foolish policies—cannot be the whole story. The sources, mostly Greek, are often prejudiced against the Persians and tend to view events from but a single point of view. No government could have lasted so long, found its way somehow through so many difficulties, and in the end actually have fought so hard against the conqueror without having much virtue with which to balance its vices.

The culture that developed under the Achaemenids was in reality the collective societies and cultures of the many subject peoples of the empire. From this mosaic it is sometimes difficult to sort out that which is distinctively Persian or distinctively a development of the Achaemenian period and therefore perhaps an early Iranian contribution to general Middle Eastern society and culture.

The languages of the empire were as varied as its peoples. The Persians, at least originally, spoke Old Persian, a southwestern dialect of Iranian (Median was a northwestern Iranian dialect), and were a nonliterate society. Their language was first written when Darius commanded that a script suitable for this purpose be invented so that he might inscribe the record of his rise to power at Bīsotūn (the inscriptions in Old Persian attributed to earlier kings were likely written during the reign of Darius or are later historical forgeries). That few could read Old Persian might be the reason why Darius at Bīsotūn established the tradition that royal inscriptions should be trilingual in Old Persian, Babylonian, and Elamite. Old Persian was never a working written language of the empire. Elamite, written on clay tablets, appears to have been the language of many of the administrators in Persis and, it may be assumed, in Elam. Archives of administrative documents in Elamite have been found at Persepolis. Aramaic (Aramaic language), however, was the language of much of the empire and was probably the language most used in the imperial bureaucracy. The beginnings of the strong influence of Aramaic on Persian, which is so evident in the Middle Persian of Sāsānian (Sāsānian dynasty) times, can already be seen in the Old Persian royal inscriptions of late Achaemenian times. (See also Iranian languages.)

Little is known of Iranian social organization in the period. In general, it was based on feudal lines that were drawn in part by economic and social functions. Traditional Indo-Iranian society consisted of three classes: the warriors or aristocracy, the priests, and the farmers or herdsmen. Crosscutting these divisions was a tribal structure based on patrilineal descent. The title king of kings, used even in the 20th century by the shahs of Iran, implies that the central authority exercised power through a pyramidal structure that was controlled at levels below the supreme authority by individuals who were themselves, in a certain sense, kings. Traditionally, the king was elected from a particular family by the warrior class; he was sacred, and a certain royal charisma attached to his person.

Such a method of organizing and controlling society undoubtedly changed under the influences and demands of imperial power and underwent much modification as Iranians increasingly borrowed social and political ideas from the peoples they ruled. Even in later times, nevertheless, there is evidence that the original Iranian concepts of kingship and social organization were still honoured and remained the ideals of Persian culture.

Iranian religion in the pre-Achaemenian and Achaemenian periods is a subject on which there is little scholarly agreement. When the Iranians first entered the dim light of the protohistoric period, they were certainly polytheists whose religious beliefs and practices closely paralleled other Indo-Iranian and Indo-European groups at the same stage in history. Their gods were associated with natural phenomena, with social, military, and economic functions, and with abstract concepts such as justice and truth. Their religious practices included, among others, animal sacrifice, a reverence for fire, and the drinking of the juice of the haoma plant, a natural intoxicant.

Probably about 600 BC there arose in the northeast of the plateau the great Iranian religious prophet and teacher Zoroaster (Zarathushtra). The history of the religion that he founded is even more complicated and controversial than the history of pre-Zoroastrian Iranian religion. Yet certain features of his religious reform stand out. He was an ethical prophet of the highest rank, stressing constantly the need to act righteously and to speak the truth and abhor the lie. In his teaching, the lie was almost personified as the Druj, chief in the kingdom of the demons, to which he relegated many of the earlier Indo-Iranian deities. His god was Ahura Mazdā, who, it seems likely, was a creation, in name and attributes, of Zoroaster. Though in a certain sense technically monotheistic, early Zoroastrianism viewed the world in strongly dualistic terms, for Ahura Mazdā and the “Lie” were deeply involved in a struggle for the human soul. Zoroaster, as might be expected, attempted to reform earlier Iranian religious practices and beliefs. He first rejected and then perhaps allowed in a modified form the practice of the haoma cult, clearly condemned the practice of animal sacrifice, and elevated to central importance in the ritual a reverence for fire. Fire worship, however, is a misnomer, because the Zoroastrians have never worshiped fire but rather have revered it as the symbol par excellence of truth.

The crucial question is: Were the Achaemenids Zoroastrians or at least followers of the prophet in the terms in which they understood his message? Possibly Cyrus the Great was, probably Darius I was, and almost certainly Xerxes I and his successors were. Such a simple answer to the question is possible, however, only if it is understood that Zoroastrianism as a religion had already undergone considerable development and modification since Zoroaster's lifetime, influenced by the beliefs and practices and by the religions of those people of the Middle East with whom the expanding Iranians had intimate contact.

The god of the Achaemenian kings was the great Ahura Mazdā, from whom they understood they had received their empire and with whose aid they accomplished all deeds. Xerxes and his successors mention other deities by name, but Ahura Mazdā remains supreme. Darius names only Ahura Mazdā in his inscriptions. More significant, however, is Darius's tone, which is entirely compatible with the moral tone of Zoroaster and, in some instances, even compatible with details of Zoroaster's theology. During the reigns of Darius and Xerxes, the archaeological record reveals that religious rituals were in force that were also compatible with an evolved and evolving Zoroastrianism. The haoma cult was practiced at Persepolis, but animal sacrifice is not attested. More important, fire clearly played a central role in Achaemenian religion.

There may have been religious overtones in the quarrel between Cambyses and Darius on the one hand and the false Bardiya—a magus, or Median priest—on the other. Certainly there were religious as well as political motivations behind Xerxes' suppression of the daeva ( deva) worshipers and the destruction of their temple. It is possible that there was some conflict among the royal Achaemenids (Achaemenian Dynasty), who were followers of one form of Zoroastrianism, the supporters of a different version of Zoroastrianism as practiced by other Iranians, believers in older forms of Iranian religion, and believers in foreign religions, which in the light of Zoroaster's teachings were reprehensible. Compromises and syncretism, however, probably could not be prevented. Though the Zoroastrian calendar was adopted as the official calendar of the empire in the reign of Artaxerxes I, by the time of Artaxerxes II the ancient Iranian god Mithra and the goddess Anāhitā (Anāhiti) (Anahīti) had been accepted in the royal religion alongside Ahura Mazdā.

Thus, in a sense, the Achaemenian kings were Zoroastrians, but Zoroastrianism itself was probably no longer exactly the religion Zoroaster had attempted to establish. What the religion of the people beyond court circles may have been is almost impossible to say. One suspects that a variety of ancient Iranian cults and beliefs were prevalent. The magi, the traditional priests of the Medes, may have wielded more influence in the countryside than they did at court, and popular beliefs and practices may have been more deeply influenced by contact with other peoples and other religions. Later classical Zoroastrianism, as known in the Sāsānian period, was an amalgam of such popular cults, of the religion of the Achaemenian court, and of the teachings of the prophet in their purer form. (See also Zoroastrianism.)

This was an imperial art on a scale the world had not seen before. Materials and artists were drawn from all the lands ruled by the great king, and thus tastes, styles, and motifs became mixed together in an eclectic art and architecture that in itself mirrored the empire and the Persians' understanding of how that empire ought to function. Yet the whole was entirely Persian. Just as the Achaemenids were tolerant in matters of local government and custom as long as Persians controlled the general policy and administration of the empire, so also were they tolerant in art so long as the finished and total effect was Persian. At Pasargadae, the capital of Cyrus the Great and Cambyses in the Persian homeland (Fārs), and at Persepolis, the neighbouring city founded by Darius the Great and used by all his successors, one can trace to a foreign origin almost all the details in the construction and embellishment of the architecture and the sculptured reliefs, but the conception, planning, and overall finished product are distinctly Persian and could not have been created by any of the foreign groups who supplied the king of kings with artistic talent. This was true also of the decorative arts, at which the Persians excelled: fine metal tableware, jewelry, seal cutting, weaponry and its decoration, and pottery.

It has been suggested that the Persians called on the subject peoples for artists because they were themselves crude barbarians with little taste and needed quickly to create an imperial art to match their sudden rise to political power. Yet excavations at sites from the protohistoric period show this not to have been the case. Cyrus may have been the leader of Persian tribes not yet as sophisticated nor as civilized as the Babylonians or Egyptians, but, when he chose to build Pasargadae, he had a long artistic tradition behind him that was probably already distinctly Iranian and that was in many ways the equal of any. To show this, two examples suffice: the tradition of the columned hall in architecture and fine gold work. The former can now be seen as belonging to an architectural tradition on the Iranian plateau that extended back through the Median period to at least the beginning of the 1st millennium BC. The rich Achaemenian gold work, which inscriptions suggest may have been a specialty of the Medes, was in the tradition of the delicate metalwork found in Iron Age II times at Hasanlu and still earlier at Marlik. Persepolis, primarily the creation of Darius and Xerxes, is one of the great artistic legacies of the ancient world, with its carefully proportioned and well-organized ground plan, rich architectural ornament, and magnificent decorative reliefs.

At the centre of the empire sat the king of kings. Around him was gathered a court composed of powerful hereditary landholders, the upper echelons of the army, the harem, religious functionaries, and the bureaucracy that administered the whole. This court lived mainly in Susa but went in the hot summer months to Ecbatana (modern Hamadān), probably in the spring to Persepolis in Fārs, and perhaps sometimes to Babylon. In a smaller version it traveled with the king when he was away in the provinces.

The provinces, or satrapies, were ruled by satraps (satrap) (governors), technically appointed by the central authority but who often became hereditary subkings, particularly in the later years of the empire. They were surrounded and assisted in their functions by a court modeled on that of the central government and were powerful officials. The great king was nevertheless theoretically able to maintain considerable control in local affairs. He was the last court of appeal in judicial matters. He directly controlled the standing military forces stationed in the provinces, though as time went on the military and civil authority in the provinces tended to become combined under the satrap. The king was also aided in keeping control in the provinces by the so-called king's eyes or, better, the king's ears—officials from the central government who traveled throughout the empire and who reported directly back to the king on what they learned. The number of provinces and their boundaries varied greatly from time to time; at the beginning of Darius's reign there were 20 provinces. In general, as time went on, the number increased, partly because of the need to reassert control over the satraps by decreasing their power base, partly because the feudal structure that underlay Persian society required rewarding more and more people with a role in government, and partly because the original 20 provinces were undoubtedly simply too large to permit efficient administration.

The army was a particularly important element within the empire. It, too, developed and changed with time. After Cyrus the Persian tribal levy, based on the responsibility of all male Persians to fight for the king, was replaced by a professional standing army supplemented by a troop levy from the subject peoples in times of intensive military activity. The elite of the standing army were the 10,000 “immortals,” (Ten Thousand Immortals) composed of Persians and Medes, 1,000 of whom were the personal guard of the king. The person who controlled this elite guard, as did Darius on the death of Cambyses, usually controlled all. The troops of the imperial levy fought alongside the regular army in national units, were armed according to their individual customs, but were usually officered by Persians. Permanent bodies of troops were stationed at strategic points throughout the empire, and, to judge from the garrison at Elephantine in Egypt, these were actually military colonies, firmly settled into the local countryside. Greek mercenaries were used with increasing frequency in later years, and many Greeks fought faithfully for Persian silver.

Both the civil and the military administration, as well as public and private trade, were greatly facilitated by the famous royal Achaemenian road system (roads and highways). Communications throughout the empire were better than any previous Middle Eastern power had maintained. The famous road from Susa to Sardis in western Asia Minor is the best known of these imperial highways. It was an all-weather road maintained by the state. Over it ran a governmental postal system based on relay stations with remounts and fresh riders located a day's ride apart. The speed with which a message could travel from the provinces to the king at Susa was remarkable.

On the whole, Persian rule sat lightly on the subject peoples, at least under the early Achaemenids. It was a conscious policy of Cyrus and Darius to permit conquered nations to retain their own religions, customs, methods of doing business, and even to some extent forms of government. This policy was exemplified by Cyrus's attitude toward the Babylonians, which led to his being accepted as the rightful successor of Nabonidus, his willingness to permit the Jews to return to Palestine and to their own way of life, and his successors' concern that this promise be honoured; Cambyses' behaviour in Egypt and his acceptance by the Egyptians as founder of a legitimate new Egyptian dynasty; and the policy adopted under Mardonius toward the Ionian cities following their rebellion. Perhaps even in the later empire, rebellious peoples, governments, and leaders were too often forgiven and not suppressed with the thoroughness sometimes characteristic of other regimes. Lapses in this policy, such as Xerxes' violent reaction to rebellion in Babylon, stand out in the record.

Law played an important role in the administration of the empire, and stories of Persian justice abound in the Greek sources. Darius particularly wished to be remembered as the great lawgiver, and law reform was one of the cornerstones in his program for reorganizing the empire. To judge from the Babylonian evidence, two sets of law, possibly administered by two sets of courts, were in force in the provinces. One was the local law, undoubtedly based on custom and previous local codifications; the other was the Persian, or imperial, law, based ultimately on the authority of the great king. A new word for law appeared in the Middle East in Achaemenian times, the Iranian dāta, and was borrowed by the Semitic languages used in the empire. In Babylonian and Aramaic, sources give evidence for Persian judges called by the Iranian word dāta-bar. These were probably the judges of the imperial courts.

With legal reform came reform and unification of tax structures. The tax structure of the empire was apparently based on the principle that all of the conquered lands were the actual property of the king. Thus taxes (taxation) were rather rents, and the Persians and their land, Fārs, by virtue of not being a conquered people or land, were always tax-free. Each province was required to pay yearly a fixed amount in gold or silver, and each vassal state paid a fixed tribute in kind. Again going on the Babylonian evidence, in previous times agricultural taxes had been levied in fixed amounts regardless of the fluctuating quality of the harvest, but under Darius all land was surveyed, an estimate of its yield (based on an average of the harvests over several years) was from time to time established, and taxes were levied in fixed amounts based on a percentage of that average yield. This was not quite an income tax, since it was not based on a percentage of each year's production, but it was at least a reasonable figure based on a reasonable production average.

Breakdowns often occurred in the Achaemenids' effort to maintain a productive balance between local social structures, customs, laws, and government and the demands of the empire. The failure of the Persians to find such a balance when dealing with what was for them an extremely strange system of social and political organization—the Greek polis, or city-state—probably lay at the heart of their never-ending troubles in Ionia as much as did the power and ambitions of mainland Greeks. Yet even the Ionians, at the best of times, often realized the mutual advantages and benefits of the king's peace and a unified western Asia under a tolerant central administration.

The economy of the empire was very much founded on that king's peace; it was when the peace broke down with ever-increasing frequency during the last century of Achaemenian rule that the economy of the empire went into a decline that undoubtedly contributed significantly to the eventual political and military collapse. Wealth in the Achaemenian world was very much founded on land and on agriculture. Land was the principal reward that the king had available for those who gave service or who were in positions of great political or military power in the empire. Under Darius there was a measure of land called a “bow” that was originally a unit considered sufficient to support one bowman, who then paid his duty for the land in military service. At the other end of the scale were enormous family estates, which often increased in size over the years and which were or became hereditary holdings. They were often administered by absentee landlords. Such major landholdings were, as one would expect, usually in the hands of Iranians, but non-Iranians were also able to amass similar wealth and power, thereby testifying once again to the inherent tolerance with which the empire was administered. The Achaemenids themselves took a positive role in encouraging agriculture by investing state funds and effort in irrigation and the improvement of horticulture.

They also invested in and endeavoured to promote trade (international trade), a major source of imperial wealth. The effect of the state-maintained road system on the encouragement of trade has already been mentioned. Equal attention was paid to developing seaborne trade. State-sponsored voyages of exploration were undertaken in order to search for new markets and new resources. Darius completed a project, begun by the Egyptians, that connected the Nile to the Red Sea by a canal, so that routes across the Arabian Sea and into the Persian Gulf could be used to link the eastern and western ends of his empire. As part of the same program, port development on the Persian Gulf coast was encouraged. Imperial standardized weights and measures, efforts to develop and use coinage, and standardizing that coinage in the king's name were all policies intended to encourage commerce and economic activity within the realm.

Banking also played a role in the economy. Documents have survived from a family banking business in Babylonia—the house of Murashu and sons of Nippur—covering the years c. 455–403 BC; the firm evidently prospered greatly by lending money and by acting as a middleman in the system of tax collection. Interest rates were high, but borrowers were numerous.

As time went on, there were clearly more and more such borrowers, for the later empire is marked by a general economic decline. The principal cause of this decline was the unsettled political conditions, but other, more indirect causes were unwise government interference in the economy, overtaxation, and the removal of too much hard money from the economy. Gold and silver tended to drain into the treasury of the central government from the provinces, and too little found its way back into general circulation. Disastrous inflation was the result. The large sums of money paid to foreign mercenaries and as bribes to foreign governments must also have contributed to an unfavourable balance of payments that in turn stimulated inflation. Such conditions hardly strengthened the empire and must have contributed, in ways that cannot be documented with certainty, to the political unrest that was their own main cause.

Ultimately, the achievement of the Achaemenian Persians was that they ruled with such creative tolerance over an area and a time that, for both the Middle East and for Europe, included the end of the ancient and the beginning of the modern world. In one sense, the ancient Middle East died when Cyrus marched into Babylon. Others would argue that its death came when Alexander burned Persepolis. The question remains open. What is clear is that the Achaemenian Empire—the largest anyone had ever yet tried to hold together and one that was not surpassed until Rome reached its height—was a profound force in western Asia and in Europe during an important period of ferment and transition in human history. That era was one of major developments in art, philosophy, literature, historiography, religion, exploration, economics, and science, and those developments provided the direct background for the further changes, along similar lines, that made the Hellenistic period so important in history. Hellenism probably would not have been possible, at least not in the form we know it, if it had had to build directly on the rather more narrow and less ambitious bases of the individual civilizations of Babylon, Egypt, or Greece. In a sense, the Achaemenian Persians passed on a concept of empire that, much modified by others, has remained something of a model of how it is possible for diverse peoples with variant customs, languages, religions, laws, and economic systems to flourish with mutual profit under a central government. In narrower terms, but for the Iranians themselves no less important, the Achaemenian Empire is seen as the beginning of the Iranian nation, one of the pivotal peoples in the modern Middle East.

Between 334 and 330 BC Alexander completed the conquest of the whole Achaemenian Empire. (For the story of the conquest, see Alexander the Great and ancient Greek civilization: Alexander the Great (ancient Greek civilization).) Alexander's burning of the royal palace at Persepolis in 330 symbolized the passing of the old order and the introduction of Greek civilization into western Asia. Greek and Macedonian (Macedonia) soldiers settled in large numbers in Mesopotamia and Iran. Alexander encouraged intermarriage and fostered Greek culture, but he also retained a large part of the Achaemenian administrative structure and introduced Oriental elements and Greek political institutions.

Alexander left no heir. His death in 323 BC signaled the beginning of a period of prolonged internecine warfare among the Macedonian generals for control of his enormous empire. By the end of the 4th century BC, Seleucus I Nicator had consolidated his control over that part of Alexander's territory that had corresponded to the Achaemenian Empire. Seleucus—who, with his son Antiochus I Soter, assumed supreme power—established a government with two capitals: Antioch on the Orontes River in Syria and Seleucia on the Tigris River (Seleucia on the Tigris) in Babylonia. The greatest part of western Asia—from the Aegean to the Punjab—belonged to this vast Seleucid kingdom, and to its diverse and varied populace must be added several allied Greek cities, both in Greece and in Asia Minor. (See also 620 (Mesopotamia, history of).)

As he was finishing the conquest of eastern Iran—and at a moment when his attention was being drawn toward the conquest of India—Alexander was confronted by two human factors that were of the greatest importance for the future of his empire. The first of these was the powerful local aristocracy of this part of the Achaemenian Empire, which held enormous properties and dominated the indigenous population. The second was the nomad population that for centuries had wandered along the northern and northeastern frontiers of Iran.

Alexander seems to have admired greatly the barons of eastern Iran; he had taken note of their ardour during the two years of hard and constant fighting in his conquest of northeastern Iran. Realizing how such a force could benefit the future of his empire, Alexander convoked an assembly of Bactrian nobles. He ordered 30,000 young men to be chosen for training in the Macedonian military disciplines. He understood the importance and effectiveness of the Iranian light cavalry armed with the bow, and his army would make use of this training in its march toward the plains of India. Alexander married Roxana of Sogdiana, daughter of a chief of one of the conquered countries, thereby symbolizing the union of the two peoples.

But Alexander was not unaware that other measures were needed to ensure his control of these vast territories. He founded many new cities (urban planning), or refounded some that were already in existence. Many of these were placed strategically along the northern frontiers as protection. Almost half of these new cities were located in the high (eastern) satrapies. This policy of Alexander's would soon be abandoned by the Seleucids, whose efforts at city planning were mostly confined to their western possessions. In contrast with Alexander, the Seleucids were unable to maintain the good rapport with the eastern Iranian nobility that Alexander had believed essential. And this deficiency, a result of the Seleucids' “pro-Macedonian” policies, was one of the principal causes for the progressive decline of the Seleucid empire.

The second of the human factors, the nomads, inhabited the immense territories beyond the northern frontiers. They fought constantly with the settled populations but could nevertheless occasionally ally with them in the face of necessity. When Alexander arrived on the banks of the Jaxartes (Syr Darya) River, it marked the limit of the “civilized” world; beyond stretched the Eurasian wilderness. The Roman historian Quintus Curtius recounts Alexander's meeting with a delegation of Scythians who gave him a warning. They told him,

These words sum up what the nomad world represented to an empire that stretched several thousand miles from east to west. The settled population knew the threat only too well. Alexander was not the first to cross swords with the nomads. Cyrus II, founder of the Achaemenian Empire, had paid with his life while fighting them, and Darius I, believing he could take them from behind through southern Russia, suffered a crushing defeat in his campaign against the Scythians along the shores of the Black Sea.

If the nomads and the eastern Iranian nobility were the two dominant factors in the decline of the Seleucid kingdom and if the events they provoked were some of the principal causes for the exhaustion and eventual fall of that state, these same causes later played a significant role in the collapse of Parthian power. Parthia was undermined by an aristocracy that retained its military power and refused to bend before the royal will or to give up its meddling in the country's politics. In the meantime the kingdom's unruly nomadic neighbours to the north and the northeast, at the cost of the lives of several Parthian sovereigns, weakened the kingdom and sometimes added a complementary element to the often numerous intrigues of the pretenders to supreme power during the course of the almost half a millennium of the existence of the Parthian kingdom.

In the struggle for power after Alexander's death, Seleucus I (Seleucus I Nicator) brought under his control the whole eastern part of Alexander's empire. But even before he had consolidated his control over this territory, the eastern provinces on the Indian frontier had begun to revolt. By about 304 BC Seleucus was forced to abandon these to Candra Gupta I (Chandra Gupta I), the founder of the great Maurya empire in India. This was a serious loss to the Seleucids, for they lost not only the Indian territory conquered by Alexander but also frontier districts west of the Indus River. As recompense, Seleucus received 500 elephants, which he took back with him to Syria. From this time on, the west was dominant in the Seleucids' politics, to the detriment of their eastern possessions. This near disinterest of the Seleucids in the far-off eastern regions must have alienated the Greeks who had settled there, far from their homeland, and the thought of taking back their full independence could not have been far from their minds.

Soon afterward (c. 290–280 BC) the two eastern provinces of Margiana and Aria suffered an invasion by nomads. But the invasion was repelled, and the nomads were pushed back beyond the Jaxartes. Demodamas, a general to the first two Seleucid kings, crossed the river and even put up altars to Apollo, ancestor of the dynasty. Alexandria in Margiana and Heraclea in Aria, founded by Alexander, were rebuilt by Antiochus I under the names Antioch and Achaea, respectively, and a wall nearly 100 miles (160 km) long was put up to protect the oasis of Merv against future invasions, the menace of which was never far away. Patrocles received a commission to explore the Caspian Sea.

Seleucus I and his successors hoped to Hellenize Asia and held the conviction that the Greeks and Macedonians were a superior people and the bearers of a superior civilization. A network of cities and military colonies was built to assure the stability of a state whose inhabitants would be Asians. The Greek language made deep inroads, especially among the families of those numerous Greeks who married the local women and among those engaged in commerce. But after the 2nd century BC and the slowing of the Greco-Macedonian immigration, the Greek language lost ground and the local element became dominant.

The people of Iran, particularly those in the upper stratum of society, borrowed nothing from Hellenism but its exterior forms. Even the Iranians who lived in such cities as Seleucia or Susa do not seem to have been deeply affected by Greek ideas.

The victories of Alexander had brought the Greeks to the limits of the known world. But less than a century after Alexander's death there began a great movement back, propelled by stirring peoples in the Iranian world. In a movement westward from the 3rd century BC, the Sarmatians (Sarmatian) occupied the northern shore of the Black Sea. While driving back their close relatives, the Scythians, they succeeded in “Sarmatizing” the Greek cities along its shores. At the end of the 3rd century, there began in Chinese Turkistan a long migration of the Yuezhi, an Iranian people who invaded Bactria about 130 BC, putting an end to the Greco-Bactrian kingdom there. (In the 1st century BC they created the Kushān dynasty (Kushan dynasty), whose rule extended from Afghanistan to the Ganges River and from Russian Turkistan to the estuary of the Indus.) Finally, the Parni, a nomadic or seminomadic people from Iran, appeared in the mid 3rd century BC. Taking a median direction between the Sarmatians and Yuezhiuezhi (Yuezhi), the Parni gained control of the Seleucid satrapy of Parthia and created the Parthian (Ashkanian) kingdom. The Parthian state restored Achaemenian power for nearly half a millennium, and its arrival coincided with the expansion of Rome and played a significant role in the destinies of the world during the last three centuries BC and the first two centuries AD.

The empire of the Seleucids, like that of the Achaemenids before them, was shaken by revolts of the satraps. The difficult situation in the west and the grave reverses suffered by the royal house accelerated the weakening of the Macedonian kingdom. The loss of its eastern possessions in the 3rd century BC, however, proved fatal to the Seleucid cause. Diodotus I, a Greek who found himself at the head of the satrapy of Bactria, led a revolt that brought independence about 250 BC; at about the same time, Arsaces led the Scythian Parni into Parthia and defeated Andragoras, establishing an independent native dynasty.

Parthia was the first province to detach itself from the Seleucid empire, just as it had been the first to rise up on the occasion of the accession of Darius the Great. Andragoras, though he did not declare himself king, showed his independence by minting his own coins. At this time Parthia was one of the poorer of the high satrapies, caught between the mountains and the great central desert and without large agricultural resources. This satrapal independence might seem surprising if it were not for the fact that the main route for the silk trade crossed right through Parthia over a distance of more than 100 miles (160 km). The tolls the caravans paid must have produced a sizable income.

The defection of Diodotus I is still easier to understand. Bactria, a vast country of a “thousand cities,” was located at the junction of the routes to China and India, and it was rich in cultivable land. The Greco-Bactrian kingdom founded by Diodotus expanded rapidly, embracing Sogdiana and Aria and extending southward and southeastward.

Being at some distance from the west, Diodotus and his successors gradually adopted the customs and lifestyles of their subjects. The closer these ties were drawn, the stronger became the loyalty of the Bactrians. It is believed that the separation of Diodotus from the Seleucids might, over the long term, have seemed to the Bactrians and Sogdians as the realization of their political destiny, and they might have looked on these satraps as men acting in their interest. For more than a century (230–130 BC) this kingdom held the frontiers and barred the route to the nomads.

Daho-Parno-Parthian tribes “chose chiefs for war and princes for peace” from among the closest circle of the royal family. They were famous for their breeding of horses, their combat cavalry, and their fine archers. Alexander encountered them during his Bactrian campaign, and the Greek writers who recorded his reign remarked on their agility and effectiveness as horsemen. They were a people who kept the traditions of patriarchal tribal organization. The Parni, with Arsaces at their head, took the province of Parthia after having beaten Andragoras; soon neighbouring Hyrcania was annexed, and the Parni reached the Caspian Sea. Arsaces had himself crowned in the city of Asaak, and the tribe took the name of the Parthians, their close relatives, which was derived from a word meaning “exiled.” Their language was closely related to Scythian and Median. The dynasty these people produced never broke its links with the people, and rare was the Arsacid dynastic sovereign who did not turn to his people in time of danger.

Although the two new kingdoms, that of Arsaces I's Parthians and the Greco-Bactrian kingdom of Diodotus I, sprang up almost simultaneously and very near each other, there were notable differences between them. The motivating force behind the rebellion in Bactria was an association—or perhaps even a collaboration—between the local nobility (large landholders who dominated the whole indigenous population) and the local Greek community. Both groups were opposed to the Macedonian domination represented by the Seleucid dynasty.

The makeup of the Parthian kingdom seems to have been different. It was essentially built on the relationship of the inhabitants of Parthia to the neighbouring tribes outside the static frontiers—an ethnic mass, half nomadic and half settled, that inhabited the north of Iran. The success of Arsaces and his men was based on their strength, their spirit, and the weakness of their enemies. The Greek element present in Parthia does not seem to have played a role similar to that played by its counterpart in Bactria. In fact, the Parthians, at least initially, may have been hostile to the local Greek populations. During their war with Antiochus III (see below (Iran, ancient)), they massacred all the Greek inhabitants of the city of Syrinx in Hyrcania.

Arsaces seems to have enjoyed great fame among the tribes. His name remained linked with the names of the sovereigns of this dynasty, who succeeded each other for the four and a half centuries of the Parthian state. His image regularly appeared on the obverse of Parthian coins until the end of the period.

The rupture of the communications link between the Seleucid capitals and the east caused by Arsaces' success placed Diodotus in a difficult situation. He seems to have wanted to collaborate with Seleucus II Callinicus in a campaign he was preparing against the Parthians. The death of Diodotus (c. 234 BC) and the accession of his son, Diodotus II, reversed matters, for the young successor changed his father's policy and joined with Arsaces. It was not until 232 or 231 BC that Seleucus arrived in the east to put down the rebellion. Arsaces, who had remained closely allied with the nomads to the north, sensed his own weakness in the face of Seleucus's army and fled to the home of the Apasiacae, or “Scythians of the Waters.” Seleucus tried to cross the Jaxartes but, having suffered losses at the hands of the nomads, decided to return to Syria after receiving alarming news from the west. He made peace with Arsaces, who recognized his suzerainty.

From that time on, Arsaces changed his policy: he acted no longer as a nomad but rather as a chief of state—a worthy successor to the Seleucids, whose example he followed, in Parthia. He had himself crowned. Besides Asaak and Dārā (an impregnable fortress), he founded such cities as Nisā (Nisa), where he would be buried. These new cities were usually named for the king or the dynasty. Arsaces seems not to have infringed on the rights of the Greeks and Macedonians living in these cities, perhaps hoping to win their support. From the beginning, while maintaining the autonomy of the cities, he made use of propaganda to ensure their continuing obedience. He installed his capital at Hecatompylos, on the Silk Road. His death is dated between 217 and 211 BC.

Arsaces' successor, Artabanus I (reigned c. 211–191 BC), sometimes known as Arsaces II, continued the work of consolidation. Artabanus, already solidly established in Parthia and Hyrcania, tried to extend his possessions toward Media. But events in the neighbouring Greco-Bactrian kingdom worked against him: Diodotus II (accused, it is thought, of treason to Hellenism through his alliance with the nomads) lost his throne, which passed to Euthydemus by the time the Syrian army of the Seleucid king Antiochus III (the Great) arrived in Hyrcania.

The wave of revolts by the eastern satraps, which began a movement away from unity in the state, also affected western Iran; the beginning of the reign of Antiochus (223–187 BC) was marked by the dissidence of Molon and his brother Alexander, satraps of Media and Persis, respectively. Antiochus did not undertake his campaign for recovery of the high satrapies—a project his father had planned and never carried out—until 212 BC. At that time his kingdom stretched no farther east than Media, Persis, Susiana, and Carmania. His operations against Artabanus were successful; he took Hecatompylos and crossed the mountains separating it from Parthia, which he occupied. Artabanus fled and took refuge with the friendly Apasiacae, as had his father, Arsaces. However, the conflict between the Seleucids and Parthia was ended by a compromise, just as it had been at the time of the invasion of Seleucus II. Because a much more important struggle, against the Bactrian kingdom of Euthydemus, awaited Antiochus, he preferred to make peace with Artabanus, to whom he accorded the title of king in exchange for recognition of his fealty, and he obliged the Parthian to send troops to reinforce the Syrian army. The rear of the Seleucid king was safeguarded, but the two provinces held by Artabanus were definitively lost by the Macedonians.

The period following Antiochus's campaign against the Parthians was marked by a strong resistance by the Bactrian cavalry at the frontier and by a Seleucid siege of Bactra, for two years the Bactrian capital (208–207 BC). There, too, the Seleucid king made peace: Euthydemus, like Artabanus, kept his title of king. Demetrius, son of Euthydemus, married a daughter of Antiochus the Great, thus preserving his political prestige.

Having acquired war elephants and provisions for his army in Bactria, Antiochus crossed the Hindu Kush into the Kabul valley, where he concluded a pact with the Indian king Sophagasenos, secured still more elephants, and returned by way of southern Iran. The results of this long campaign were meagre. Antiochus recognized the independence of two kingdoms, that of the Parthians and that of Euthydemus, which previously had been no more than satrapies. The struggle must have weakened these two states, but, after their status was legalized, they proceeded to reestablish their material and military resources.

Precise information is not available concerning the reign of Priapatius (c. 191–176 BC), who succeeded Artabanus and whose name appears in documents found in excavations at Nisā. Under his son Phraates I (reigned c. 176–171 BC), the young Parthian kingdom seems to have recuperated sufficiently to have taken up once again its expansionist activities. It attacked Media, succeeded in the conquest of the Mardi tribe near the Caspian Sea, and set up a defense of the “Caspian Gates,” an important strategic point of penetration in Phraates' possessions. Overturning tribal tradition, which reserved the succession to the throne to the eldest son, he wisely designated as a successor—even though he had several sons—his brother Mithradates.

The accession of Mithradates I about 171 BC opened a new period in the destinies of the Parthian kingdom, which historians call “phil-Hellenistic” and which lasted until AD 12. This period was characterized by a strong Hellenistic cultural influence, manifested in the use of the Greek language and in particular in the arts, where, however, national traditions were not completely abandoned.

Parthian military, political, and economic power expanded considerably following the accession of Mithradates I. The king began with an attack on the Greco-Bactrian kingdom, which at the time was going through a period of weakness; then he turned against the west and declared himself independent of the Seleucids. To show his complete independence—he was the first of the Parthian sovereigns to do so—he began issuing coins bearing his likeness wearing a royal diadem like the Seleucid kings. On the reverse side was a representation of Arsaces, ancestor of the Parthian dynasty, seated on an omphalos (hemispheric altar) and holding a bow, in imitation of Seleucid coins that showed Apollo in the same way, as the ancestor of the Seleucids.

The Seleucid king Antiochus IV Epiphanes took action against Mithradates but was killed at Tabae (or Gabae, probably present Eṣfahān). His death brought about a widespread dislocation of the Macedonian kingdom, which crumbled into several smaller states. Toward 160 BC the power to unite most of the high satrapies and other eastern satrapies could come only from the Parthians, who under Mithradates began the assault. They occupied Media in 155, which opened the route to Mesopotamia. In 148–147 Mithradates reached Ecbatana, where he moved his capital. Rhagae (Rayy) was “refounded” and given the dynastic name of Arsacia, and in 141 Mithradates took Seleucia on the Tigris and was recognized king of Babylonia. His forces conquered Susiana and Elymais, either at this time or after 139. In 141 he was obliged to leave Hyrcania for his eastern possessions, which were evidently being menaced by hostile movements of the nomads. There he spent the remaining three years of his reign.

The Seleucid king Demetrius II, probably aware of Mithradates' difficulties in the east, undertook an effort to recover Mesopotamia, but after a few successes he suffered defeat and was taken prisoner (139 BC). He was sent to Hyrcania and was married there to a daughter of Mithradates, who by this union became related to the house of Seleucus. The army of Demetrius included Greco-Bactrian and Elymaian troops—which is understandable—as well as men from Persis, or Persians, who by their cooperation with the Macedonians seem to indicate their opposition to the expansionism of the Parthians, whom they considered foreigners and conquerors. Iran under the Parthians was an empire but not yet a nation.

Like his father, Mithradates I, Phraates II (reigned c. 138–128 BC) was to remain for some time in the eastern provinces. He also endured a last Macedonian attempt to break the Parthian advance. Antiochus VII Sidetes—brother of Demetrius II, who had been taken prisoner—assembled a powerful army, which once more included men of Persis and Elymais. The strength in numbers and the wealth of this army made an impression on contemporaries, who reported that even the simple soldiers wore shoes cobbled with gold. Phraates was beaten in several battles, but time worked on his side. With the arrival of winter, Antiochus quartered his troops in several localities in Media. The local population, exasperated by the undisciplined Syrian soldiery, rose up in revolt. Antiochus was killed and his son taken prisoner (129 BC). Thanks to the loyalty of the Medians, whose sentiments contrasted with those of the Persians, Phraates was victorious. The year 129 BC was a turning point in the history of the eastern Mediterranean: Greco-Macedonian domination received a decisive blow; it would survive for only 46 more years.

The route to great acquisitions in the west seemed to open before Phraates, if the nomads did not stop him. Weakened in his struggle against Antiochus VII, he called on the Śaka nomads to the north of his frontiers for aid, promising them payment. The reinforcements arrived too late to be of use; he sent them back, which provoked them to revolt and pillage the countryside. The Greek prisoners drafted by Phraates into his army participated in the pillaging, and Phraates lost his life fighting them. The same fate was reserved for his successor and uncle, Artabanus II (c. 128–124/123 BC). The Śaka were pushed back with some difficulty toward Drangiana, to which they gave their name, Sakastan (Sīstān) (Sīstān). Another branch of the vast nomadic movement crossed the Oxus and put an end to the Greco-Bactrian kingdom, on the ruins of which the powerful Kushān kingdom was to be built.

The second stage of the phil-Hellenistic period extends from the first quarter of the 2nd century until about 30 BC and embraces a period when Parthia reached the apogee of its power and worldwide territorial expansion.

The reign of Mithradates II, from 123 to 88 BC, constitutes the most glorious chapter of Parthian history. It put an end to the ambitions of Artabanus's son Himerus, left by his father as governor of Mesopotamia, and brought Hyspaosines, king of Mesene (Characene), who had extended his possessions too far toward the north, back into submission. In the east the Śaka were on the move—soon an independent state would be formed there that would push toward eastern Iran and India; in the 1st century BC two dynasties, the Indo-Scythian and the Indo-Parthian, whose members would remain closely linked to the Arsacid dynasty, were to reign in that region. They would disappear after being absorbed by the Kushān kingdom.

The eastern frontiers of Mithradates II incorporated Margiana and Aria. Once order was restored in the east, the king turned toward the west: he placed Tigranes II (Tigranes II The Great) (the Great) on the throne of Armenia, and, extending his hegemony over this kingdom and over eastern Asia Minor, he organized pressure on the last Seleucids. A meeting with Rome (ancient Rome), which had already formed a “Province of Asia” in Asia Minor, became inevitable and took place in 92 BC on the Euphrates River between the Roman general Lucius Cornelius Sulla (Sulla, Lucius Cornelius) and the Parthian ambassador Orobaze. Mithradates II wisely refused to agree to follow in the Roman path and preferred to retain his neutrality in the struggle between Rome and Mithradates VI Eupator of Pontus. Rome in the west and Parthia in the east met as Alexander's successors and, with a common accord, settled the inheritance. The two parties recognized the Euphrates as a common frontier. It seems there was no longer a question of either an alliance or a signed convention. Upon his return, Orobaze paid with his head for the lèse-majesté he had committed by accepting a seat lower than Sulla's at their meeting.

For the first time, Parthian power entered into direct contact with the Chinese empire and received an embassy from the Han emperor Wudi (140–87 BC), who dispatched an escort of 20,000 men to meet the Parthians. The Chinese were particularly interested in the horses raised in Fergana, which they needed to create a cavalry to fight the nomadic Xiongnu on their northern border.

At the zenith of his power, Mithradates II took the title of “king of kings”; in the east as well as in the west, his empire achieved a position of power and stability previously unknown. He maintained diplomatic relations with the two greatest world powers, Rome and China. Mithradates I, Phraates II, and Mithradates II were the true creators of the Parthian state, winning for it military and economic victories and raising it to a level comparable to that of the Achaemenian Empire. After the death of Mithradates II, a short period of intrigue and rivalry saw the succession, in turn, of Gotarzes I, Orodes I, and Sanatruces. The latter came to power late in life and was replaced in 70 BC by his son, Phraates III (70–58/57 BC), under whom sustained contacts with Rome took place.

In 69 BC the Roman general Lucius Licinius Lucullus (Lucullus, Lucius Licinius), in charge of looking after Roman interests in the East, attempted to lure Phraates III into an alliance that would help Rome in its struggle against Pontus and Armenia, but the Parthian king, while still maintaining “friendly” relations with Rome, retained his neutrality. An agreement with the Romans renewed the Euphrates line as a frontier. Three years later the Roman general Pompey the Great replaced Lucullus and succeeded in concluding a real alliance with Phraates III. This proved, however, to be of short duration, for affairs in Armenia, aggravated by Roman operations on Parthian territory, had brought the two empires to a parting of the ways. Pompey replied to Phraates' protestations by occupying Gordyene, a vassal state of the Parthians, and addressed Phraates with the simple title “king.” Pompey did not trouble himself over entering into direct relations with the sovereigns of Media and Elymais, vassals of Phraates. The position taken by the Romans toward the king of kings was rather more like that of conquerors than of allies. Pompey's policy became clear: from the Caucasus to the Persian Gulf, he hoped to create a wall of states friendly to Rome that would encircle Parthia, in preparation for Roman conquest.

That action fell within the jurisdiction of the Roman triumvir Marcus Licinius Crassus (Crassus, Marcus Licinius). As early as 57 BC a conflict with Rome broke out over the case of Mithradates III (58/57–55 BC), who, opposing Orodes II (c. 57–37/36 BC), his brother (both having killed their father, Phraates III), fled to Syria and asked the legate Aulus Gabinius (Gabinius, Aulus) for aid and asylum. The Roman Senate forbade Gabinius to involve himself in the dispute over the succession to the Parthian throne. Three years later the tension between the two powers was settled in bloody fashion, and the rupture was consummated in 53 BC. Without provocation, the army of Crassus—the only one of the triumvirs without military glory (Julius Caesar was conqueror of Gaul, and Pompey was conqueror of the Middle East)—crossed the Euphrates. Orodes protested and invoked the treaty of friendship in vain. Crassus refused to reply until he arrived at Seleucia on the Tigris. It was a brutal breaking of all the agreements concluded in 69 and 66 BC.

The Battle of Carrhae (Carrhae, Battle of) (53 BC), with the Parthians led by Surenas with his light and heavy cavalry, cost Rome seven legions and the lives of Crassus and his son. Through Surenas's brilliant victory the routes to Iran and India were closed to Rome, and its ambitions in the Orient were so weakened that the Euphrates became not only a political but also a spiritual frontier; no effort at Romanization beyond it was possible any longer. A united Greco-Iranian front protected Asia against the Romanization of Iranianized Hellenism and destroyed the myth of Roman invincibility.

The insignia of the Roman legions fell into Parthian hands, and 10,000 Roman prisoners were sent into captivity in Margiana. The victory over Crassus had great repercussions among the peoples of the East. It shook the Roman position in Asia Minor, Syria, and Palestine, while it restored the Parthians' confidence in their power and in their ability to resist Rome and promised them a dominant position among the peoples of the East. According to the Greek writer Plutarch, the severed head of Crassus was brought to Orodes like a hunting trophy while he was attending a presentation of Euripides' play The Bacchae.

The Parthian counterthrust in 52–50 BC under the command of Prince Pacorus (Pakores) was not crowned with success. The Arsacid (Arsacid dynasty) army did not know how to organize long campaigns or how to lay siege to fortified cities. But soon, civil war in Rome reinforced the position of the Parthians, and Pompey, after being defeated by Caesar (Caesar, Julius), thought of taking refuge among them. It is thought that Orodes, taking advantage of this lull, succeeded in resolving difficulties in the east with the Yuezhiuezhi, even perhaps with the Kushān. In 48 BC, with Pompey dead, Caesar was the absolute master of the Roman world. He was preparing to avenge Crassus's defeat when he was assassinated in 44 BC. The duty of following through on Caesar's project fell to Mark Antony (Antony, Mark). Pacorus, anticipating Antony, crossed into Syria after having concluded an agreement with Quintus Labienus, a Roman commander on the side of Caesar's assassins who had gone over to the Parthians. The successes of the two armies were startling: Labienus took all of Asia Minor, Pacorus all of Syria and Palestine. For nearly two years all the western provinces of the Achaemenids remained in Parthian hands. In Rome it was rumoured that the Parthians were planning to invade Italy itself. But the successes of the Arsacid armies were as ephemeral as they were remarkable. Disagreement between the two generals weakened their effect. In 39 BC Labienus was conquered by Roman forces under Publius Ventidius (Ventidius, Publius) and slain. Asia Minor was recovered by the Romans, and the following year the same fate struck Pacorus and his conquests.

Under Orodes II the Parthians had reached the zenith of their power: in the west the Arsacids had for a short time reestablished the empire of the Achaemenids almost in its entirety. Their successes in the east seem to have been equally important. Their capital was moved to Ctesiphon, where a military camp was transformed into a great metropolis, facing Seleucia across the Tigris. At Nisā (Nisa) the city was expanded, the royal palaces were enlarged, and the royal hypogea (catacombs) were enriched with precious pieces of fine Greco-Iranian art.

In 37 BC Orodes was assassinated by his son Phraates IV, who also did away with his brothers and his eldest son. In 36 BC Mark Antony began to carry out the revenge Caesar had planned. He brought his army to Armenia, through which he planned to enter Media and attack Parthia from the north. But cold weather and Phraates' cavalry combined to force Antony to abandon the fight and return to Syria. In 34 BC he launched another campaign and again suffered heavy losses, and his power struggle with Octavian forced him to abandon his plans for war against the Parthians.

About 30 BC Tiridates II, (Tiridates II) a pretender to the throne of Parthia supported by Rome, forced Phraates IV to leave Mesopotamia and take refuge with his eastern neighbours, the Scythians, who restored him to power. Driven out, Tiridates took refuge at Rome. He returned again in 26 BC, after which Phraates was able to definitively reestablish his power at the same time that Octavian was inaugurating the imperial period of Roman history.

The new stage in the phil-Hellenistic period began about 31 BC, when, after his victory over Mark Antony, Octavian (now Caesar Augustus (Augustus)) was the sole master in Rome. Before that, however, he had already proposed to Phraates an alliance and a treaty ending the war. The Battle of Carrhae and Antony's defeat had raised Parthia to a major power in the eyes of Rome. Augustus put pressure on Phraates IV through the pretender Tiridates and even tried military intervention. In the end a pact was signed in 20 BC that allowed Roman prisoners and the insignia of the conquered legions to be returned. A new stage began in relations between the two states, marked by the conclusion of a real peace that recognized the Euphrates as a frontier between them. Phraates was dealt with as the sovereign of a great nation. Rome renounced its ambitions in the east, and Augustus inaugurated a policy of respect. The two states could do nothing but profit from the agreement, for a defeat would have been fatal to either power and a victory hazardous. The caravan route to India and China was reopened. Augustus received ambassadors from the many eastern peoples, including the Indo-Scythians and the Sarmatians. The only country in the east where Rome remained active was Armenia.

All obstacles, however, were not necessarily eliminated. There remained the question of Armenia: if it was controlled by Rome, it would be a channel for penetration into Parthia from the north, but if it was controlled by Parthia, it would offer an outlet on the Black Sea, over which Rome asserted its authority. The rivalry of the two powers over this country would remain for centuries a stumbling block to peace.

Toward 10 or 9 BC Phraates sent his four sons and grandsons to Rome, a gesture that was both one of confidence in a “friendly” power and also a guarantee that his throne would pass to his son by Musa, an Italian slave girl given him by Augustus. This son would assassinate his father with his mother's help and occupy the throne as Phraates V from 2 BC to AD 4 after having married his mother.

The end of the “phil-Hellenistic” period is marked by the clash of the ruling class with foreign influences that had penetrated life in Parthian society. These influences came from Rome and were often introduced by princes of the Arsacid house returning from stays abroad. The short reign of Orodes III (AD 4–6/7) was followed by that of Vonones I (7/8–11), a son of Phraates IV who, because of his Roman habits, was driven out by the Parthian nobility, whose role by that time had become dominant in internal politics and dynastic questions. Vonones' fall brought about a change in the destinies of the country.

A new and important period in Parthian history, often called “anti-Hellenistic,” embraces a century and a half, from AD 12 to 162. It is characterized by an expansion of the native Parthian culture and an opposition to all things foreign. The weakness of the reigning dynasty opened wide avenues to the nobility to involve themselves in the official existence of the state. They chose the sovereign whose reign opened the first stage in this new period.

The king chosen by the barons to replace Vonones was Artabanus III (reigned 12–38). They were certainly mistaken in believing they would find in him an easy instrument to manipulate. Artabanus was the son of a viceroy of Hyrcania and was Arsacid only on his mother's side. Under his rule Parthia entered a brilliant but troubled era, one completely dominated by the personality of this violently anti-Roman sovereign who was eager to drive Rome out of Asia. However, after he failed to place his son on the throne of Armenia, for years Artabanus avoided precipitating matters with Rome and dedicated himself to internal reforms, among which centralization was the most important.

The humbling of the great nobles, an enterprise in which he was sustained by the lesser nobles, became necessary. He had to reduce the hereditary privileges the barons had carved out for themselves. It was also necessary to reorganize the states that made up the kingdom. He put princes of his family on the thrones of Mesene, Persis, Elymais, Atropatene—all little states that were governed by men loyal to the throne. But it proved impossible for him to put down a revolt in the eastern possessions, where the Indo-Parthian king Gondophares (Gondophernes) declared himself independent (c. 19) and took the title “king of kings.”

It is thought that the position taken toward the city-states, about which precise information is lacking, was the reason for the seven-year-long revolt of Seleucia on the Tigris. The fighting there took place between the Greek and Hellenized elements and the Semites, who demanded their right to participate in the autonomy of the city and who supported pretenders against Artabanus III.

A new attempt to place a son on the throne in Armenia angered Rome, which, with the aid of the nobility, sent for Tiridates III, a pretender the barons had crowned at Ctesiphon. Artabanus was forced to take refuge with the Dahae, who helped him win back his throne. In 37 a meeting with a representative of Rome on a bridge in the middle of the Euphrates allowed an agreement to be reached that maintained the status quo in Armenia and recognized Parthian sovereignty with the river as the frontier. Artabanus, a strong personality, did not seek to impose his kingdom as a world power, but he did not hesitate to make plans to regain the western provinces, the former Achaemenian possessions.

The period from 51 to 122 is one in which the Parthian state slowly dissolved and decomposed into several small countries, and various parties lay claim to the throne—an inevitable result of the weakness of the central power. In the 1st century AD the Parthian empire, according to the Roman historian Pliny, was composed of 18 kingdoms, 11 in the north and seven in the south, some governed by Arsacid princes and others by local dynasties. In 58 Hyrcania became independent. In the realm of external affairs, an effort was made to maintain good relations with Rome, especially because of the new kingdom of the Kushān, which was causing concern on the eastern frontiers. It might be for this reason that in 87 Parthia sent an embassy to neighbouring China to the east of the Kushān. Internally, the ethnic upsurge became more accentuated.

After the short reign of Vonones II (51), the throne passed to Vologeses I (reigned 51–80), an ardent anti-Roman. One of his brothers, Vonones, was made king of Media. Vologeses I wanted his second brother, Tiridates, to be king of Armenia—putting him in position to break with Rome, which opposed him militarily. Upon orders from Nero, the Roman general Corbulo (Corbulo, Gnaeus Domitius) secured Armenia, but his operations were broken off by the exchange of ambassadors. An agreement was finally reached: in 66 Tiridates left for Rome with his whole family, surrounded by a retinue of princes and 3,000 Parthian nobles. He received from Nero the crown of Armenia. Parthian control and the end of hostilities were announced by closing the doors to the Temple of Janus.

Nationalist sentiment—which had been expressed under Artabanus III in a genealogical table invented to prove the Achaemenian descent of the Arsacid house—also manifested itself under Vologeses I: the Avesta, the holy book of the Iranians, was compiled, and coins were issued on which, for the first time, Pahlavi (Pahlavi alphabet) (Middle Persian) characters were added to the Greek legend.

In 78 Pacorus II came to the throne, to be supplanted in 79 by the ephemeral Artabanus IV (80/81), who was then replaced permanently by Pacorus II. During his reign the country showed signs of a profound decomposition. The barons refused to obey the crown. In the provinces the army and the finances were in the hands of the nobility. Aristocrats occupied the highest positions, which became hereditary. Plots with Rome were hatched, and the nobility felt itself the equal of the dynasty, ready to revolt in defense of their privileges. Externally, the dynasty was unable to count on Rome, which constantly plotted in support of new pretenders. In 109/110 Pacorus II was eclipsed by Osroes, his brother or brother-in-law, but he maintained limited power until his death in 115/116.

In 114 the emperor Trajan invaded Armenia. In vain did the king put his crown at Trajan's feet—he was defeated by the Roman soldiery. With Armenia occupied, the emperor descended with his army into Mesopotamia. All of Babylonia was taken, and Ctesiphon, the capital, fell into the hands of the Romans, who carried off a daughter of Osroes and the golden throne of the Parthian kings. Victorious, Trajan went as far east as the Persian Gulf. Iranian reaction was not long in coming. Faced with the gravity of the Roman offensive, all the princes of the royal house, formerly divided by internal strife, united against the invader. At Ctesiphon Trajan crowned a new vassal king, but revolt was in the wind, and attempts to disunite the Parthian chiefs failed. The Romans suffered losses, and, after a reverse on the walls of Hatra, Trajan abandoned the campaign and died on his way home. Trajan's successor, Hadrian (reigned 117–138), abandoned all pretensions to Armenia, Mesopotamia, and Assyria.

Hadrian's desire for peace seems to have been sincere. He sent back Osroes' daughter, promised to return the golden throne, and did not try to profit from the long power struggle between Osroes and Vologeses III (Vologeses III (or II)) (or II). He even invited Osroes to come to Rome.

Thus ensued four decades of peace with Rome. The status quo it maintained with its western neighbour seems even to have been a necessity for Parthia, the expansion of the Kushān kingdom on the eastern frontiers having reached the peak of its power under King Kaniṣka (Kanishka). Accurate information about the relations between the Kushān and the Parthians is not available, but this long peace sought with Rome suggests that certain precautions were necessary for the kingdom of Iran.

The 40 years' peace was succeeded by almost uninterrupted hostilities with Rome, with varied success; Parthia was more vulnerable because of the exposed position of its capital.

The reigns of Vologeses III (or II; c. 105/106–147?) and especially Vologeses IV (Vologeses IV (or III)) (or III; 148–192), the latter not having to dispute the throne with a pretender, could by their lengths be a sign that the country might have experienced a certain stability. But underneath the apparent calm the intrigues continued, with Rome receiving embassies from the Hyrcanians, the Bactrians, and doubtless from the Kushān.

A new clash with Rome came in 161, this time on the initiative of Vologeses IV (or III), who considered himself strong enough to attack. He occupied Armenia, crossed the Euphrates, and invaded Syria, which for two centuries had not seen Parthian cavalry. And, although the country had been Roman since the time of Pompey, the Syrian population, which included Jews driven from Palestine by the Romans, received the Parthians as liberators. The situation became so serious that Lucius Verus (Verus, Lucius), co-emperor with Marcus Aurelius, was dispatched to the east with strong reinforcements taken from the fronts on the Danube and the Rhine. The Romans retook Armenia (163) and succeeded in a campaign similar to Trajan's: Dura-Europus was taken and remained Roman until its destruction by the Sāsānids; Seleucia on the Tigris, despite the welcome it reserved for the Romans, was sacked; and in 164 or 165 for the second time Ctesiphon fell into the hands of Romans, who razed the royal palace.

Once more success was not continuous. The Roman army had come from Armenia and crossed through Azerbaijan, where it was exposed to plague. Contaminated, the Roman army was sorely tried by disease and obliged to retreat, but not definitively. Lucius Verus, repeating his campaigns in Armenia and northern Mesopotamia, inflicted heavy losses on the Parthians.

The tensions between the two states did not diminish when Vologeses V (Vologeses V (or IV)) (or IV; reigned 191–208/209) supported a pretender (Pescennius Niger) against Septimius Severus (Severus, Septimius). The latter became emperor in 193 and began operations that permitted him to occupy first northern and then southern Mesopotamia and, for the third time in a century, Ctesiphon. The Parthians in their retreat adopted a scorched-earth policy. As under Trajan, the starving Roman army went back up the Tigris, failed in its attempt to take Hatra, and left the country.

Since 208 Pāpak (Bābak), a lesser prince of Persis, had been preparing a revolt, which his son Ardashīr I finally declared openly. A battle took place between him and Artabanus V in 224; the Parthian was killed, and the throne of Iran passed into the hands of the Sāsānids, a new dynasty, originally from Fārs, the cradle of the Achaemenids.

The Iran of the Parthians—in the middle between the Romans in the west and the Kushān in the east, a region strategically crucial for international commerce—maintained open roads, created cities, and encouraged exchanges that were the lifeblood of this great empire stretching from the portals of China and India to the Roman Empire. Tolerant in religion, it was Parthia that contributed to the dissemination of Buddhism to China, where a Parthian prince spread the word of Buddha near the mid 2nd century AD. For nearly half a millennium Parthia pursued its great ambition to recover the western provinces of the Achaemenids. Undermined by internal weaknesses, Parthia finally succumbed, leaving its great dreams to its successors, the Sāsānids.

At the beginning of the 3rd century AD, the Arsacid empire had been in existence for some 400 years. Its strength had been undermined, however, by repeated Roman invasions, and the empire became once more divided, this time between Vologeses VI (or V), who seems to have ruled at Ctesiphon, on the left bank of the middle Tigris in what is now Iraq, and Artabanus V, who was in control of Iran and whose authority at Susa, in southwestern Iran, is attested by an inscription from 215. (See also Mesopotamia, history of: The Sāsānian period (Mesopotamia, history of).)

It was against Artabanus V that a challenger arose in Persis. Ardashīr I, son of Pāpak and a descendant of Sāsān, was the ruler of one of the several small states into which Persia had gradually been divided. His father had taken possession of the city and district of Istakhr (Estakhr), which had replaced the old residence city of Persepolis, a mass of ruins after its destruction by Alexander the Great in 330 BC. Pāpak was succeeded by his eldest son, who was soon killed in an accident, and in AD 208 Ardashīr replaced his brother. He first built for himself a stronghold at Gūr, named, for its founder, Ardashīr-Khwarrah (“Ardashīr's Glory”), now Fīrūzābād, southeast of Shīrāz in Fārs. He subdued the neighbouring rulers and in the process disposed of his own remaining brothers. His seizure of such areas as Kermān, Eṣfahān, Elymais, and Mesene—to the east, north, and west of Fārs, respectively—led to war with Artabanus, his suzerain. The conflict between the two rivals lasted several years, during which time the Parthian forces were defeated in three battles. In the last of these, the battle on the plain of Hormizdagān (224), Artabanus was killed.

There is evidence to support the assumption that Ardashīr's rise to power suffered several setbacks. Vologeses VI (or V) struck coins at Seleucia on the Tigris as late as AD 228/229 (the Seleucid year 539). Another Parthian prince, Artavasdes, a son of Artabanus V, known from coins on which he is portrayed with the distinguishing feature of a forked beard, seems to have exercised practical independence even after 228. Numismatic evidence further reflects the stages of Ardashīr's struggle for undisputed leadership. He appears on his coins with four different types of crowns: as king of Fārs, as claimant to the throne before the battle at Hormizdagān, and as emperor with two distinctly different crowns. It has been suggested that this evidence points to two separate coronation ceremonies of Ardashīr as sovereign ruler, the second perhaps indicating that he may have lost the throne temporarily.

According to al-Ṭabarī (Ṭabarī, aṭ-), the Muslim historian (9th–10th century), Ardashīr, after having secured his position as a ruler in western Iran, embarked on an extensive military campaign in the east (227) and conquered Sakastan (modern Sīstān), Hyrcania (Gorgān), Margiana (Merv), Bactria (Balkh), and Chorasmia (Khwārezm). The inference that this campaign resulted in the defeat of the powerful Kushān empire is supported by the further statement of al-Ṭabarī that the king of the Kushān was among the eastern sovereigns, including the rulers of Tūrān (Quzdar, south of modern Quetta) and of Mokrān (Makran) (Makran), whose surrender was received by Ardashīr. These military and political successes were further extended by Ardashīr when he took possession of the palace at Ctesiphon and assumed the title “king of kings of the Iranians” and, across the Tigris River, when he refounded and rebuilt the city of Seleucia under the new name Veh-Ardashīr, the “Good Deed of Ardashīr.”

Shortly after his accession, Shāpūr was faced with an invasion of Persia by the emperor Gordian III (reigned 238–244):

Several years later, in 256 (or 252), another confrontation between the Persians and Romans occurred:

including Antioch, the capital of Syria, itself. A third encounter took place when the emperor Valerian came to the rescue of the city of Edessa (Şanlıurfa), Syria (modern Urfa, Turkey), which was besieged by the Persian army:

The source for these quotations is Shāpūr's own account of the events. It was unknown until 1938, when expeditions sponsored by the Oriental Institute of the University of Chicago discovered a long inscription on the walls of an Achaemenian building known as the Kaʿbe-ye Zardusht (“Kaaba of Zoroaster”). The text is in three languages, Sāsānian Pahlavi (Middle Persian), Parthian, and Greek. Besides the narrative of the military operations, the inscription provides a description of the Persian empire of the time and an inventory of the Zoroastrian religious foundations established by Shāpūr to commemorate his victorious wars. These foundations were fire temples dedicated to the “soul” (memory) of the founder himself, members of the royal family, and prominent officials who had served under Shāpūr and his predecessor. The list of the officials, who are specified by the positions they held, throws light on the administrative organization of the empire.

In contrast to his father, who claimed to be “king of kings of Iran” (shāhanshāh īrān), Shāpūr I assumed the title “king of kings of Iran and non-Iran” (shāhanshāh īrān ud anīrān). This formula was retained by his successors as the regular designation of the Sāsānian emperors. The hereditary local dynasties, which under the Arsacids had ruled many of the most important provinces, were to a large extent abolished. Instead, such areas as Maishān (Mesene), in western Iran, and Sakastan (Sīstān), in eastern Iran, were now ruled by members of the Sāsānian family, who were appointed by the sovereign with the title of shāh (king). Among such provincial governors, precedence was often given to the heir to the throne, who was placed in control of large territories, such as the former Kushān empire (Kūshānshahr) and Armenia, and given the title “great king” (wuzurg shāh). This arrangement lasted until the early 4th century AD, and such emperors as Shāpūr I and Hormizd II are known to have first held the title kūshānshāh as governors of the areas of Bactria, Sogdiana, and Gandhāra. Next in the hierarchy came the few remaining hereditary vassals, such as the kings of Iberia (now Georgia) in the Caucasus, and the chief nobles of the empire, among whom the Warāz, Sūrēn, and Karēn families retained their prominent position from Parthian times. Next in line were the satraps, whose importance had diminished and who were now no more than the administrators of larger cities or court officials.

The list of provinces given in the inscription of Kaʿbe-ye Zardusht defines the extent of the empire under Shāpūr, in clockwise geographic enumeration: (1) Persis (Fārs), (2) Parthia, (3) Susiana (Khūzestān), (4) Maishān (Mesene), (5) Asūristān (southern Mesopotamia), (6) Adiabene, (7) Arabistān (northern Mesopotamia), (8) Atropatene (Azerbaijan), (9) Armenia, (10) Iberia (Georgia), (11) Machelonia, (12) Albania (eastern Caucasus), (13) Balāsagān up to the Caucasus Mountains and the Gate of Albania (also known as Gate of the Alans), (14) Patishkhwagar (all of the Elburz Mountains), (15) Media, (16) Hyrcania (Gorgān), (17) Margiana (Merv), (18) Aria, (19) Abarshahr, (20) Carmania (Kermān), (21) Sakastan (Sīstān), (22) Tūrān, (23) Mokrān (Makran), (24) Paratān (Paradene), (25) India (probably restricted to the Indus River delta area), (26) Kūshānshahr, until as far as Peshāwar and until Kashgar and (the borders of) Sogdiana and Tashkent, and (27), on the farther side of the sea, Mazun (Oman). This empire, considerably more extensive than that controlled by the Arsacid dynasty, was governed by members of the royal family and by appointed officials directly responsible to the throne. The greater degree of centralization thus attained by the Sāsānian government partly explains its increased military effectiveness in comparison with the Arsacid administration. Tight organization of the numerous central and provincial officials, whose ranks in the bureaucratic structure on different levels were strictly defined, also contributed toward general administrative efficiency.

Another trend that developed in the Sāsānian period, although it had already made itself felt under the Arsacids, was a strict principle of dynastic legitimacy. For a usurper not of the royal blood to come to the throne was an extremely rare occurrence, though it was in fact accomplished by Bahrām VI Chūbīn in 590. Loyalty was given, however, to the whole royal house, rather as it was in the later Ottoman Empire. The person of the individual ruler was a matter of comparatively lesser importance, and one member of the dynasty could readily be removed and replaced by another. In accordance with this principle of legitimacy, Persian tradition carried the Sāsānian line back to the Achaemenids and, ultimately, to the kings of the legendary period.

The ancestors of Ardashīr had played a leading role in the rites of the fire temple at Istakhr, known as Ādur-Anāhīd, the Anāhīd Fire. With the new dynasty having these priestly antecedents, it seems only natural that there would have been important developments in the Zoroastrian religion during the Sāsānian period. In fact, the evolution of Zoroastrianism as an organized religion into something resembling its modern form can be regarded as having begun in this period. Under the Parthians, local magi (magus) (priests) had no doubt continued to perform the traditional ceremonies associated with the old Iranian deities, the fire cult, the creed preached by Zoroaster, with its emphasis on the worship of Ahura Mazdā, and even the cults of cosmopolitan deities that were introduced in the Hellenistic period and later.

Under the Sāsānians, stress was increasingly placed on the fire cult and the worship of Ahura Mazdā. Strong mutual relationships, furthermore, were developed between religion and the state, and an ecclesiastical organization was set up in which every local district of any importance had its own mobed (“priest”; originally magupat, “chief priest”). At their head stood the mobedān mobed (“priest of priests”), who, in addition to his purely religious jurisdiction, appears, especially in later times, to have had a more or less decisive voice in the choice of a successor to the throne and in other matters of state. There is also some evidence that the mobeds, by virtue of their proficiency in reading and writing in general and in the interpretation of the sacred scriptures in particular, performed the duties of registrars and scribes in semireligious or nonreligious matters, like the Christian clergy in medieval Europe. This situation in turn makes it likely that the priestly library buildings not only contained the sacred texts, charters, and other church records but also served as repositories of local archives, title deeds, and other documents of a legal nature. The building known as Kaʿbe-ye Zardusht and referred to as a bun-khānag (“foundation house”) may well have served this very purpose.

In the matter of religious practice, the theology of the Sāsānians appears to have developed from that of their home province of Persis. There, extraneous religious influences were limited. The opposition between the good spirit of light and the demons—between Ahura Mazdā (Ormizd) and Angra Mainyu (Ahriman) (Ahriman)—remained the essential dogma. All the other gods and angels were restricted to the role of subordinate servants of Ahura Mazdā, whose highest manifestation on earth was not so much the sun or the sun god Mithra (Mihr) but rather the holy fire guarded and attended by his priests. At the same time, the names of such deities as Verethraghna (Wahrām), Mithra, and Anāhitā (Anāhiti) (Anāhīd) were still associated with the names of fire temples or classes of fires. Divine names were also used to designate the 30 days of each month and of the 12 months of the year, plus five epact days, called gahānīg, to align the lunar with the solar year.

All the prescriptions of purity were scrupulously observed. The elaborate ritual still maintained in modern times by the Parsi for the purification and custody of the sacred fire was no doubt observed under the Sāsānians. The officiating priest was girt with a sword and carried in his hand the barsman (barsom), or bundle of sacred grass. His mouth was covered to prevent the sacred fire from being polluted by his breath. The practice of animal sacrifice, abhorred by the modern followers of Zoroaster, is attested for the Sāsānian period at least as late as the reign of Yazdegerd I (399–420). On the days of the important festivals, such as Nōgrūz (Nōrūz) ( Nōrūz), the first day of the vernal equinox, and on the day of Mihragan (the 16th day of the seventh month), the sacred fire was displayed to the faithful (wehden) at nightfall from some vantage point. Under the Sāsānians the injunction not to pollute the earth by contact with corpses but to expose the dead on mountaintops to vultures and dogs was strictly observed. Ahura Mazdā preserved his character as a national god who bestowed victory and world dominion on his worshipers. In rock-relief sculptures he appears on horseback as a god of war.

Theology was further developed, and an attempt was made to modify the old dualistic concept by considering both Ahura Mazdā and Angra Mainyu as emanations of an original principle of infinite time (Zurvān (Zurvanism)). This doctrine enjoyed a certain degree of official recognition in early Sāsānian times. In the reign of Khosrow I (531–579), however, the “sect of the Zurvānites” was declared to be heretical. The chief trend of Sāsānian religion, apart from the process of being institutionalized, was toward elaborating its ritual and doctrine of purity. A complete and detailed system of casuistry was developed, which dealt with all things allowed and forbidden and with the forms of pollution and the expiation of each. One of the consequences of this development was that increasing emphasis was placed on orthodoxy and rigorous obedience to priestly injunctions. Nonorthodox and heretical cults and forbidden manners and customs came to be regarded as a pollution of the land and a serious offense to the true God. It was the duty of the believer to combat and destroy the unbelievers and the heretics. In short, the tolerance of the Achaemenids and the indifference of the Arsacids were gradually replaced by religious intolerance and persecution.

Despite his priestly family origin, Ardashīr himself seems not to have been the person responsible for initiating these new directions in religious affairs. It was once believed that the institutionalization of the Zoroastrian church and the codification of its scriptures and beliefs were the work of a high priest named Tansar, a contemporary of Ardashīr I, of whose activities an account is preserved in the Letter of Tansar, contained in the History of Ṭabaristān (Tārīkh-e Ṭabaristān) by the Persian writer Ibn Isfandiyār (flourished 12th–13th century). New inscriptional evidence, however, suggests that, if Tansar was, in fact, a historical personage, his role in religious matters was overshadowed by Kartēr (Karder). The latter, an ehrpat (or herbed, “master of learning”) and mobed (or magupat, “priest”) already prominent under Shāpūr I, appeared during the reigns of Bahrām I (reigned 273–276) and Bahrām II (276–293) as the dominant figure in the Zoroastrian church. As stated in the Kaʿbe-ye Zardusht inscription of Kartēr, he claims credit for suppressing non-Zoroastrian religious communities in Iran (“and Jews, Buddhists, Brahmans, ‘Nazoreans,' Christians…were struck upon”), imposing orthodoxy and discipline on the priesthood (“the heretics 【ahlomog】…who in the Magus estate did not attend to the Mazdean religion and the services to the gods with discrimination, I struck them with punishment and I castigated them”), and establishing royal foundations for the maintenance of priests and of sacred fires. (See also Zoroastrianism.)

The reference in the Kartēr inscription to two sects of Christians continues the indications from Syriac sources that Christianity had by that time (the second half of the 3rd century) gained a firm footing in the lands of the Tigris and the Euphrates, where it was strongest among the Aramaic-speaking communities. Ultimately, Christian missionary effort came to expand over the whole of Iran and even beyond. As long as the Roman Empire remained pagan, the Christian communities of Iran lived undisturbed by persecution, while the Christians themselves showed outspoken hostility toward such heterodox sects as the Manichaeans and the Gnostic followers of Marcion (the Marcionites) and Bardesanes, who existed side by side with them. Once the emperor Constantine I (the Great; reigned 306–337) made Christianity the official religion of the Roman world, the Iranian Christians were drawn to feel a certain sympathy for their foreign coreligionists, and political significance came to be attached by the Sāsānian rulers to these religious connections with an often hostile foreign power. After 339 the Christians of Iran were subjected to severe persecutions at the hands of Shāpūr II and his successors. Nonetheless, substantial Christian communities survived in parts of Iran long after the end of the Sāsānian dynasty.

During the reign of Shāpūr I a new religious leader and movement made their appearance. Mani (216?–274?) was the offspring of a Parthian family resident in Babylonia (“a thankful disciple I am, risen from Babel's land”) but was himself a speaker of Aramaic. Knowledge of his teachings was greatly increased by the discovery in the early 20th century of many fragments of Manichaean literature in eastern Turkistan. Subsequently a large part of the Kephalaia, a collection of the religious injunctions of Mani, was recovered in a Coptic version found in Egypt. These texts can now be collated with the versions of Manichaean doctrines as reported by the Church Fathers, including St. Augustine (Augustine, Saint). From this cumulative documentation, to which other sources can be added, it appears, among other things, that Mani's teachings were formulated under the strong influence of Gnostic ideas and philosophy. Mani proclaimed himself to be the last and greatest Apostle of Jesus as well as the Paraclete announced in the Gospel According to John (John, Gospel According to). With the Gnostic interpretation of the Gospel, Mani tried to combine the doctrines of Zoroaster and Jesus in order to create a new religion of a universal character. There is a tradition that he made his first appearance as a teacher on the coronation day of Shāpūr (April 12, 240, or April 9, 243), but other evidence suggests that Mani was not necessarily in Iran at the time and may have been on a sea journey to India when he started preaching. He later returned and found many followers, among whom were Fīrūz (Pērōz) and Mihrshāh, governor of Maishān (Mesene) (Mesene), both brothers of Shāpūr (Shāpūr I). Even the king himself is said to have been impressed and to have granted the prophet several personal interviews. On the last such occasion, Mani presented the king with his first book, the Shāpuragān (Shabuhragan), a summary of his teachings (“dedicated to Shāpūr”) written in the Middle Persian language, which provides further evidence of a degree of royal favour. During Shāpūr's reign the religion of Mani was thus propagated in and beyond Iran. The heir to the throne, Hormizd I, was also favourably disposed toward him. Shāpūr's younger son, Bahrām I, however, yielded to pressure from the priestly establishment, and Mani was executed. After that, Manichaeism was persecuted and destroyed in Iran. Yet it maintained itself not only in the West, penetrating far into the Roman Empire, but also in the East, in Khorāsān and beyond the boundaries of the Sāsānian empire. There the seat of its leader was at Samarkand, whence it penetrated Central Asia.

Perhaps the most characteristic and certainly among the most impressive relics of Sāsānian art are the great rock sculptures (sculpture) carved on the limestone cliffs that are found in many parts of the country. The best-known groups are at Naqsh-e Rostam and Naqsh-e Rajab, both near Persepolis, and at Bishāpūr, an ancient city a few miles north of Kāzerūn in Fārs. At Fīrūzābād—the ancient Gūr, also in Fārs—are two reliefs of Ardashīr I, one depicting the overthrow of Artabanus V, the other depicting an investiture scene. Not far away, in the valley at Sar Mashhad, a representation of Bahrām II shows that king in the process of slaying two lions. At Dārābgerd, about 180 miles (290 km) southwest of Shīrāz, Shāpūr I is shown triumphing over three Roman emperors— Gordian III, Philip the Arabian (Philip), and Valerian. At Naqsh-e Bahrām, north of Kāzerūn, Bahrām III is depicted enthroned. The same ruler appears at Qaṣr-e Abū Nasr, near Shīrāz, and at Gūyom, not far from there. Sāsānian sculptured reliefs are less numerous outside Fārs, but a Sāsānian equestrian that once existed at Rayy (ancient Rhagae), southeast of modern Tehrān, was replaced in the 19th century by a representation of Fatḥ ʿAlī Shāh, a member of the then-ruling Qājār dynasty. At Salmās, near Lake Urmia, Ardashīr I is shown on horseback while receiving the surrender of a Parthian personage. There are also later Sāsānian sculptures at Ṭāq-e Bostān, near Kermānshāh, showing Ardashīr II, Shāpūr III, and Khosrow II. In many of these representations the Sāsānian kings can be identified by their individual crowns.

The most ambitious and celebrated architectural achievement of the dynasty is the vast palace at Ctesiphon, built by Khosrow II (590; 591–628), a part of which is still standing. It is known as the Ṭāq Kisrā and is notable for its great barrel vault in baked brick, a typically Sāsānian architectonic device. Many Sāsānian buildings can also be seen in Fārs, where the characteristic construction is of limestone blocks embedded in strong mortar. The most important of these are near Shīrāz: the palace of Ardashīr I to the south at Fīrūzābād and a small, well-preserved palace at Sarvestān, southeast of Shīrāz, in which the rooms are roofed with domes and squinches, features often found in Sāsānian architecture. Excavations at Bishāpūr, or Shāhpūr, have revealed some mosaic floors and other features of this important Sāsānian town. Numerous fire temples of the period survive, especially in Fārs; these are square buildings roofed by a dome over four arches. Sāsānian remains of considerable extent also exist at Qaṣr-e Shīrīn, on the road from Baghdad to Tehrān, and at Gondēshāpūr, modern Shāhābād, south of Dezfūl.

The acquaintance with Greek language and literature maintained by the Arsacid court had begun to decline during the last century of that dynasty. Greek versions nonetheless accompany the Parthian and Middle Persian texts of the inscriptions of Ardashīr I and Shāpūr I, as in the case of the Kaʿbe-ye Zardusht inscription. Later inscriptions, however, are only in Parthian and Middle Persian, as in the case of the inscription of Narses at Paikuli.

Most of the comparatively few remaining examples of literature in Book Pahlavi (Pahlavi language)—a form of Middle Persian somewhat different from that used in the Sāsānian inscriptions—is of late or post-Sāsānian date in its actual form, if not in content. This is partly due to the fact that the transition from an oral to a written literary tradition (both religious and secular compositions) took place in the latter part of the Sāsānian era. A passage in a religious text states that “it is proper to consider the living spoken word more weighty than the written.” It should be added that most Sāsānian literary remains are primarily of religious and historical rather than of literary interest. Just as foreign learning appears in religious works, likewise foreign prose works of entertainment came to Persia, where they were translated; among them, in the time of Khosrow I, were Hellenistic romance literature and Indian books of tales, such as Kalīlag and Dimnag, based on the Indian Pañca-tantra, or the legends of Barlaam and Josaphat (Balauhar and Budasaf).

In foreign policy the issues under the Sāsānian kings remained, as of old, the defense and, when possible, the expansion of the eastern and western frontiers. The successful military campaigns in the eastern areas by Ardashīr I and Shāpūr I, which resulted in the annexation of the western part of the Kushān empire, have already been mentioned.

In the west the old contest for northern Mesopotamia—with the fortified cities of Carrhae (Harran), Nisibis (Nusaybin), and Edessa (Şanlıurfa)—continued. The Sāsānians were all the more eager to regain and retain control of Armenia because there the Arsacid dynasty still survived and turned for protection to Rome, with which, in consequence, new wars continually broke out. In the reign of Bahrām II (276–293), the Roman emperor Carus (282–283) invaded Mesopotamia without meeting opposition and reached Ctesiphon. His sudden death, however, caused the Roman army to withdraw. Bahrām II had been prevented from meeting the Roman challenge by the rebellion of his brother, the kūshānshāh Hormizd, who tried to establish an independent eastern empire. This attempt ended in failure, however, and Bahrām II appointed his younger son, the future Bahrām III, as viceroy of Sakastan (Sīstān). After Bahrām II died, Narses, the youngest son of Shāpūr I, contested the succession of Bahrām III and won the crown. In memory of his victory, Narses erected a tower at Paikuli, in the mountains west of the upper Diyālā River, which was discovered in 1843 by the British Orientalist Sir Henry Rawlinson. Decorated with busts of Narses, the monument has a long inscription in Parthian and Middle Persian that tells the story of the events. In 296 Narses was forced to conclude a peace treaty with the Romans by which Armenia remained under Roman suzerainty and certain areas in northern Mesopotamia (Mesopotamia, history of) were ceded to Rome. By this treaty, which lasted for 40 years, the Sāsānians withdrew completely from the disputed districts. The Roman Empire had meanwhile become Christian, and the Syro-Christian populations of Mesopotamia and Babylonia began to feel sympathy with Roman policies for religious reasons. Christianity also became predominant in Armenia after its king adopted the Christian faith in 294. The Sāsānian emperors consequently felt the need to consolidate their Zoroastrianism, and efforts were made to perfect and enforce state orthodoxy. All heresy was proscribed by the state, defection from the official faith was made a capital crime, and persecution of the heterodox, the Christians in particular, began. Competition between Iran and Rome-Byzantium thus took on a religious dimension.

A new war was inevitable. It was begun by Shāpūr II in 337, the year of the death of Constantine I. Shāpūr besieged the fortress city of Nisibis three times without success. The emperor Constantius II (reigned 337–361) conducted the war weakly, but Shāpūr was distracted by the appearance of a new enemy, the nomadic Chionites, on his eastern frontier. After a long campaign against them (353–358), he returned to Mesopotamia and, with the help of Chionite auxiliaries, captured the city of Amida (modern Diyarbakır, Turkey) on the upper Tigris, an episode vividly narrated by the Roman historian Ammianus Marcellinus (c. 330–395). The emperor Julian the Apostate (Julian) (361–363) reopened hostilities after the death of Constantius but died after having reached the vicinity of Ctesiphon. His successor, Jovian (363–364), was forced to give up the Roman possessions on the Tigris, including Nisibis, and to abandon Armenia and his Arsacid protégé, Arsaces III, to the Persians. The greater part of Armenia then became a Persian province.

After about two decades of disturbed reigns ( Ardashīr II, Shāpūr III, Bahrām IV), Yazdegerd I came to the throne in 399. His reign is viewed differently by Christian and Zoroastrian sources. The former praise his clemency; the latter refer to him as “Yazdegerd the Sinful.” His initial inclination toward tolerance of Christianity and Judaism was met by resistance on the part of the nobility. Because of their attitude and because of the growing fanaticism of the Christians, Yazdegerd was forced to turn to repression. After his death (420) the nobles refused to admit any of Yazdegerd's sons to the throne. But one of them, Bahrām (Bahrām V), had the support of al-Mundhir, Arab king of Al-Ḥīrah (Ḥīrah, al-) (east of the lower Euphrates) and a Sāsānian vassal, and also, apparently, of Mihr-Narseh, chief minister in Yazdegerd's last years, who was retained in office, and Bahrām eventually won the throne. As King Bahrām V (420–438), surnamed Gūr (for the onager, or wild ass), he became the favourite of Persian popular tradition, which exuberantly celebrates his prowess in hunting and in love. Unsuccessful in war with Byzantium (Byzantine Empire) (421–422), Bahrām V made a 100-year peace and granted freedom of worship to the Christians. In the east he did succeed in repelling an invasion by the Hephthalites (Hephthalite). In the following decades, however (the second half of the 5th century), Hephthalite attacks continued to harass and weaken the Sāsānians. Fīrūz (reigned 457–484) fell in battle against them; his treasures and family were captured, and the country was devastated. His brother Balāsh (484–488), unable to cope with continuing incursions, was deposed and blinded. The crown fell to Kavadh (Kavadh I) (Qobād) I, son of Fīrūz. While the empire continued to suffer distress, he was dethroned and imprisoned (496), but he escaped to the Hephthalites and was restored (499) with their assistance. The Nestorian doctrine (claiming that divine and human persons remained separate in the incarnate Christ) had by then become dominant among the Christians in Iran and was definitely established as the accepted form of Christianity in the Sāsānian empire.

Kavadh I proved himself a vigorous ruler. He restored peace and order in the land. Amida was destroyed during his campaign against the Romans in 502, but another inroad by the Hephthalites in the east compelled him to ratify a peace treaty with the Byzantines. Toward the end of his reign, in 527, he resumed the war and defeated the Byzantine general Belisarius at Callinicum (531) with the support of al-Mundhir II of Al-Ḥīrah. Earlier in his reign he had moved away from the Zoroastrian church and favoured Mazdakism, a new socioreligious movement that had found support among the people. The crown prince, Khosrow, however, was an orthodox Zoroastrian; toward the end of his father's reign, in collaboration with the chief mobed, he contrived to condemn the Mazdakites, who were destroyed in a great massacre in 528. On his father's death, after acceding as Khosrow I (531–579), he concluded peace with the Byzantine emperor Justinian (532). He reestablished Zoroastrian orthodoxy, and, although some persecution of Christian communities occurred during periods of tension with Byzantium, the restoration of peace brought about a considerable amount of religious tolerance.

Khosrow I was one of the most illustrious Sāsānian monarchs. From his time dates a new and more equitable adjustment of the imperial tax system (taxation). The levying of land revenue in kind was replaced by a fixed assessment in cash, and these assessments continued in force later under the Arab administration. His reputation as an enlightened and just ruler was high during his lifetime and later became legendary. When Justinian I closed the philosophy school in Athens in 529, the last Neoplatonists (Neoplatonism) turned to Khosrow in hopes of finding in him the true philosopher-king. Although they were disillusioned by conditions at his court, their gratitude was great when Khosrow obtained for them the right to return to Athens. From 540 onward Khosrow had been conducting a long war against Justinian, which, although interrupted by several armistices, lasted until the so-called 50 years' peace of 561. Khosrow also extended his power to the Black Sea and inflicted heavy defeats on the Hephthalites. These military successes resulted partly because the armed forces and the chain of command were reorganized several times during Khosrow's long reign.

About 560 a new nation, that of the Turks, had emerged in the east. By concluding an alliance with a Turkish leader called Sinjibu (Silzibul), Khosrow was able to inflict a decisive defeat on the Hephthalites, after which event a common frontier between the Turkish and Sāsānian empires was established. Inevitably, this alliance became a source of possible friction, and the Turks sometimes acted as an ally of Byzantium against Iran in a second war (572–579).

Khosrow bequeathed this war to his son Hormizd IV (579–590), who, in spite of repeated negotiations, failed to reestablish peace between Byzantium and Iran, and fighting occurred intermittently throughout his reign. Hormizd was unable to display the same authority as his father, and he antagonized the Zoroastrian clergy by failing to take action against the Christians. He finally fell victim to a conspiracy headed by the general Bahrām Chūbīn (Bahrām VI Chūbīn). Hormizd's son, Khosrow II, was set up against his father and forced to acquiesce when Hormizd was executed. New unrest broke out, in which Bahrām Chūbīn—though not of royal lineage—attempted to secure the throne. Simultaneously another pretender, Prince Bestām, decided to try his luck. Khosrow fled to Byzantium, and the emperor Maurice undertook to restore him by military force. Bahrām Chūbīn was routed (591) and fled to and was killed by the Turks, and Khosrow again ascended the throne in Ctesiphon. Bestām held out in Media until 596.

During the two reigns (590 and 591–628) of Khosrow II—surnamed Parvīz (the “Victorious”)—the Sāsānids achieved unprecedented splendour and material wealth. The assassination of Maurice (602) impelled Khosrow to war against Byzantium, in the course of which his armies penetrated as far as Chalcedon (opposite Constantinople), ravaged Syria, and captured Antioch (611), Damascus (613), and Jerusalem (614); in 619 Egypt was occupied. The Byzantine Empire was, indeed, at its lowest ebb.

It took the great emperor Heraclius, who was crowned in 610, many years to rebuild the nucleus of a new army. This done, however, he set out in 622 and retaliated vigorously against the Persians, whose armies were defeated everywhere. In 624 Heraclius invaded Atropatene (Azerbaijan) and destroyed the great Zoroastrian fire temple; in 627 he entered the Tigris provinces. Khosrow II attempted no resistance, and a revolution followed in which he was defeated and slain by his son Kavadh (Qobād) II (628). When Kavadh died a few months later, anarchy resulted. After a succession of short-time rulers, Yazdegerd III, grandson of Khosrow II, came to the throne in 632.

All these prolonged and exhausting hostilities drastically reduced the powers of both Byzantium and Iran. The door was open to a newly emerging force that challenged both states and religions—the Arabs. After several encounters, the fate of the Sāsānian empire was decided in the battle of Al-Qādisiyyah (636/637)—on one of the Euphrates canals, not far from Al-Ḥīrah—during which the Sāsānian commander in chief, Rostam, was killed. Ctesiphon with its treasures was at the mercy of the victors. Yazdegerd III fled to Media, where his generals tried to organize new resistance. The Battle of Nahāvand (Nahāvand, Battle of) (642), south of Hamadān, put an end to their hopes. Yazdegerd sought refuge in one province after another, until at last, in 651, he was assassinated near Merv.

With the fall of the empire, the fate of its religion was also sealed. The Muslims officially tolerated the Zoroastrian faith, though persecutions were not unknown. Little by little it vanished from Iran, except for a few surviving adherents who remain to the present day in Yazd and a few other places. Other Zoroastrians emigrated to western India, where they are now chiefly concentrated in Mumbai (Bombay). These Parsi (Persians) have preserved only a relatively small portion of their sacred writings. They still number their years by the era of Yazdegerd III, the last king of their faith and the last Sāsānian sovereign of Iran.