city and administrative centre of Orenburg oblast (region), western Russia, on the Ural River at the Sakmara confluence. Founded as a fortress in 1735 at the Ural-Or confluence, where Orsk now stands, it was moved to its present site in 1743. It was originally the military centre of the Ural Cossacks, and its commercial importance grew with trade to Central Asia, especially after the railway from Kuybyshev (now Samara) was built in 1871–73. Modern Orenburg has major engineering industries, producing heavy-industrial and agricultural machinery; it manufactures a range of consumer goods and foodstuffs. It also has gas-processing facilities. The city has teacher-training, medical, and agricultural institutes. Pop. (2006 est.) 533,872.

oblast (region), western Russia, occupying an area that extends across the southern end of the Ural Mountains. It stretches from the limestone plateaus of the Obshchy Syrt in the west, across the low Urals ridges, to the flat Turgay Plateau in the east. Most of the oblast lies in the feather-grass and fescue steppe; in the north and northwest are groves of birch and pine, especially in the Buzuluk pine forest nature reserve. Much of the steppe is plowed up, particularly as a result of the Virgin and Idle Lands Campaign of the 1950s, and agriculture is important, principally spring wheat, corn (maize), millet, and sunflowers. The economy is dominated, however, by the mining and industrial area at the southern end of the Urals, centred on Orenburg city, the oblast headquarters. Many minerals are exploited, and heavy industry—iron and steel, petrochemicals, and engineering—is highly developed. Area 47,900 square miles (124,000 square km). Pop. (2006 est.) 2,137,850.