Amur

River in east Asia, which with its tributary, the Ussuri, forms the boundary between Russia and China for much of its course. Formed by the Argun and Shilka rivers, the Amur flows for over 4,400 km/2,730 mi and enters the Sea of Okhotsk. At its mouth at Nikolevsk it is 16 km/10 mi wide.

Under the treaties of Aigun (1858) and Peking (1860), 984,200 sq km/380,000 sq mi of territory north and east of the two rivers were ceded by China to the tsarist government. From 1963 China raised the question of its return and there were border clashes in the 1960s and 1970s. In the 1990s a Boundary Commission began the demarcation of the border, and in 1997 Russia and China signed an accord agreeing the eastern portion of their common frontier.

Amur

Oblast (region) in the Russian Federation, part of the Russian Far East; area 363,700 sq km/140,425 sq mi; population (1996) 1,038,000 (65.2% urban). The main cities are Blagoveshchensk (capital), Belogorsk, and Raychikhinsk. The region is situated between the Amur River in the south and the Stanovoi mountain range in the north; it is mainly forested and has rich mineral deposits (including gold and coal). The main industries are food processing, saw-milling, and mining; the main agricultural activities are the cultivation of spring wheat, and dairy farming.