The Mekong is a trans-boundary river in Southeast Asia. It is the world's 12th-longest river and the 7th-longest in Asia. Its estimated length is 4,350 km (2,703 mi), and it drains an area of 795,000 km2 (307,000 sq mi), discharging 457 km3 (110 cu mi) of water annually.From the Tibetan Plateau the river runs through China's Yunnan province, Myanmar, Laos, Thailand, Cambodia and Vietnam.