Amur

The Amur River or Heilong River is a perennial river in Northeast Asia, forming the natural border between the Russian Far East and Northeast China. The Amur proper is 2,824 km (1,755 mi) long, and has a drainage basin of 1,855,000 km2 (716,000 mi2). If including its main stem tributary, the Argun, the Amur is 4,444 km (2,761 mi) long, making it the world's tenth longest river. (Wikipedia)