in antiquity, the area of the Carpathian Mountains and Transylvania, in present north-central and western Romania. The Dacian people had earlier occupied lands south of the Danube and north of the mountains, and the Roman province eventually included wider territories both to the north and east. The Dacians were agricultural and also worked their rich mines of silver, iron, and gold. They first appeared in the Athenian slave market in the 4th century BC; subsequently they traded with the Greeks (importing especially wine) and used Greek coins. They spoke a Thracian dialect but were influenced culturally by the neighbouring Scythians and by the Celtic invaders of the 4th century BC. The Dacians engaged Roman troops in 112, 109, and 75 BC. In about 60–50 BC King Burebista unified and extended the kingdom, which, however, split into four parts after his death.

During the reign of the Roman emperor Augustus (ruled 27 BC–AD 14) and again in AD 69 the Dacians raided the Roman province of Moesia but were beaten back. The Dacian Wars (AD 85–89) under the emperor Domitian resulted in their recognition of Roman overlordship. The Romans under Trajan reopened hostilities in AD 101 and by 106 subdued the whole country. A large part of the population was either exterminated or driven northward. The Romans seized an enormous amount of wealth (the Dacian Wars were commemorated on Trajan's Column in Rome) and immediately exploited the Dacian mines. Roman influence was broadened by the construction of important roads, and Sarmizegethusa and Tsierna (Orsova) were made colonies. The new province was divided under Hadrian: Dacia Superior corresponded roughly to Transylvania and Dacia Inferior to the region of Walachia.

In AD 159 Antoninus Pius redivided the region into three provinces, the Tres Daciae (Dacia Porolissensis, Dacia Apulensis, and Dacia Malvensis), all subordinate to one governor of consular rank. Marcus Aurelius made the provinces a single military region in about AD 168. The limits of Roman territory were probably never clearly defined, but the Romans benefitted both militarily and materially from the occupation.