Tumen

The Tumen River (Chinese: 图们江; pinyin: Túmén Jiāng, Russian: река Туманная, Korean: 두만강; Korean pronunciation: [tuman.gaŋ]), also known as the Tuman River or Duman River, is a 521-kilometre (324 mi) long river that serves as part of the boundary between China (left shore), North Korea (right) and Russia (left), rising on the slopes of Mount Paektu and flowing into the Sea of Japan. The river has a drainage basin of 33,800 km2 (13,100 sq mi).

The river flows in northeast Asia, on the border between China and North Korea in its upper reaches, and between North Korea and Russia in its last 17 kilometers (11 mi) before entering the Sea of Japan. The river forms much of the southern border of Jilin Province in Northeast China and the northern borders of North Korea's North Hamgyong and Ryanggang provinces. Paektu Mountain on the Chinese-North Korean border is the source of the river, as well as of the Yalu River. The two rivers and the region of Paektu Mountain between their headwaters form the border between North Korea and China.

The name of the river comes from the Mongolian word tümen, meaning "ten thousand" or a myriad.