city and administrative centre of Tula oblast (region), western Russia. It lies along the Upa River, which is a tributary of the Oka River. First mentioned in 1146 as Taydula, Tula became the principal stronghold on the southern approaches to Moscow in the 16th century and the centre of a series of defensive lines against Tatar attack. A stone citadel of 1530, restored in 1784 and 1824, survives. In 1552 the city successfully resisted a siege by the Tatars. During the 17th century, Tula developed into the major ironworking city of Russia. It was the site of Russia's first armament factory, built in 1712 by Peter I the Great, and remains a large armament producer. Besides iron and steel, modern Tula has a range of engineering industries. Much lignite (brown coal) is mined locally and used in the chemical industry. Samovars are a traditional manufacture. The city has mechanical, mining, and teacher-training institutes and one devoted to coal-mining research. A museum founded in 1724 displays a history of weapons. Yasnaya Polyana, the home of the writer Leo Tolstoy, is located 9 miles (14 km) southwest of Tula. Pop. (2005 est.) 465,943.

The archaeological remains near contemporary Tula are concentrated in two clusters at opposite ends of a low ridge. Recent surveys indicate that the original urban area covered at least 3 square miles (some 8 square km) and that the town probably had a population in the tens of thousands. The major civic centre consists of a large plaza bordered on one side by a five-stepped temple pyramid, which was probably dedicated to the god Quetzalcóatl. Other structures include a palace complex, two other temple pyramids (pyramid), and two ball courts. Another large civic centre stands at the opposite end of the ridge.

Separated from the main temple pyramid by a narrow alley are the partial remains of what may have been the palace of the ruler of Tula. The excavated portions consist of three great halls (hypostyle hall). Each apparently had a low bench placed along the interior walls (with projecting thrones at the midpoints), a central sunken light well, and great numbers of columns for support of the flat wood and masonry roof.

In general, the art and architecture of Tula show a striking similarity to that of Tenochtitlán, the Aztec capital, and the artistic themes indicate a close approximation in religious ideology and behaviour. In fact, many scholars believe that the Aztecs' concept of themselves as warrior-priests of the sun god was directly borrowed from the people of Tula.

oblast (region), western Russia, in the Central Russian Upland. The oblast's rolling hills, which are much dissected by river valleys and erosion gullies, are covered by both fertile and poor soils, but the natural vegetation of mixed forest or forest-steppe has in large part been cleared for agriculture since the intensive settlement of the area in the 16th century. The climate is continental, with precipitation declining from 23 inches (575 mm) in the northwest to 18.5 inches (470 mm) in the southeast. The oblast's highly developed farming includes grain cultivation (wheat and rye), dairying, livestock raising, market gardening, and sugar beet and potato growing. Since the 17th century, the area has been noted for its metallurgical industry, which has been joined in the 20th century by engineering and chemicals. A considerable amount of lignite (brown coal) has been mined there. Area 9,900 square miles (25,700 square km). Pop. (2005 est.) 1,621,908.