The Amur River, also known as the Heilong River, is a perennial river located in Northeast Asia. It serves as the natural border between the Russian Far East and Northeast China.
The Amur proper measures 2,824 km (1,755 mi) in length and possesses a drainage basin of 1,855,000 km2 (716,000 mi2). When including its main stem tributary, the Argun, the river's total length reaches 4,444 km (2,761 mi), making it the tenth longest river in the world.