The Mekong is one of the world’s major rivers. It is the 11th-longest river in the world, and the 12th-largest by volume (discharging of water annually). Its estimated length is , and it drains an area of . 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 Asian regional association, Mekong-Ganga Cooperation is named after this river. The extreme seasonal variations in flow and the presence of rapids and waterfalls have made navigation extremely difficult.