Amur River, a river in northeast Asia. The Chinese call it Heilong Jiang, meaning “Black Dragon River.” Measured from the junction of its main headstreams, the Shilka and Argun rivers, the Amur is about 1,800 miles (2,900 km) long. With the Shilka and Onon, the system measures about 2,700 miles (4,350 km) in length. More than 1,000 miles (1,600 km) of its course forms the boundary between Russia and China. From its source the Amur winds generally southeastward and then northeastward until it empties into the Tatar Strait, which connects the Sea of Japan and the Sea of Okhotsk.
The Amur's main tributaries are the Zeya, Bureya, Ussuri, and Songhua rivers. During the ice-free season (May-November) the Amur is navigable by barge in its lower course. It flows through important mining and lumbering regions. Rich fishing grounds lie near its mouth. The Kaluga sturgeon, one of the world's largest freshwater fishes, is found only in the Amur.