Tumen River

The Tumen River (Tumangang) is the second-longest river on the Korean Peninsula. In all, it extends 520 kilometers, first flowing northeast from the slopes of Mount Paektu and then southeast through narrow gorges to the East Sea or Sea of Japan. The river is rather shallow due to the dry climate of its drainage basin, which has an area of 24,296 square kilometers. However, in its lower reaches, the Tumen is as wide as 300 meters and is navigable for 80 kilometers. The river is frozen for three to four months of the year.

The Tumen River became the permanent northern-frontier border of Korea when six garrison forts were established there during the reigns of the Choson monarchs T'aejo (1392–1398) and Sejong (1418–1450). In 1909, the river was officially recognized as the international border between China and Korea. A Sino-Russian agreement in 1860 gave Korea and Russia a 16.5-kilometer border demarcated by the Tumen River. Korea and Russia have not signed any treaty to verify this border, but it is undisputed.

The Tumen River and its tributaries have been developed into a valuable source of hydroelectric energy. Efforts are being made to transform the Tumen River area into a free-trade zone.