(əgyēn'bʊryät') or Aga Buryat (äg'ə bʊryät') , administrative division (1995 pop. 79,400), 7,000 sq mi (19,000 sq km), S Siberian Russia, Chita region. Formed in 1937, the area follows the Onon River. Aginskoye, the capital, is an administrative center. The chief occupation is livestock herding, while in the warmer areas grain is grown. Buryats, Buddhist descendants of the Mongols, make up about 54% of the area's population, with the remainder being mostly Russians (40%).