The Mekong River is one of the world’s major rivers. It is the world's 10th longest river and the 7th longest in Asia. (discharging 475 km3/114 cu mi of water annually). Its estimated length is 4,350 km (2,703 mi), and it drains an area of 795,000 km2 (307,000 sq mi). From the Tibetan Plateau it runs through China's Yunnan province, Burma, Thailand, Laos, Cambodia and Vietnam. All except China and Burma belong to the Mekong River Commission. A South- and Southeast Asian regional association, the Mekong-Ganga Cooperation, is named after this river and the Ganges river. The extreme seasonal variations in flow and the presence of rapids and waterfalls have made navigation extremely difficult.
The Mekong basin is one of the richest areas of biodiversity in the world. More than 1200 species of fish have been identified and there could be possibly as many as 1700. Fishing is a very important part of the economic activities in the area and a vital source of protein in the local diet. Estimates indicate that some 120 fish species are commercially traded but most of the fishery is based on 10-20 species.
The difficulty of navigating the river has meant that it has divided, rather than united, the people who live near it. The earliest known settlements date to 2100 BCE, with Ban Chiang being an excellent example of that early Iron Age culture. The earliest recorded civilisation was the 1st century Indianised-Khmer culture of Funan, in the Mekong Delta. Excavations at Oc Eo, near modern An Giang, have found coins from as far away as the Roman Empire. This was succeeded by the Khmer culture Chenla state by around the 5th century. The Khmer empire of Angkor was the last great Indianized state in the region. From around the time of the fall of the Khmer empire, the Mekong was the frontline between the emergent states of Siam and Tonkin (North Vietnam), with Laos and Cambodia, then situated on the coast, torn between their influence.