Brahmaputra

It rises in the Himalayan glaciers as the Tsangbo (or Zangpo) and runs east through Tibet, to the mountain mass of Namcha Barwa, passing through gorges over 5,000 m/16,000 ft deep. Turning south, as the Dihang, it enters India and flows into the Assam Valley near Sadiya, where it is now known as the Brahmaputra. It flows generally west until, shortly after reaching Bangladesh, it turns south and divides into the Brahmaputra proper, without much water, and the main stream, the Jamuna, which joins the Padma arm of the Ganges. An enormous delta has been built by the Ganges and Brahmaputra rivers and their distributaries, and the floodplains are heavily cultivated in both India and Bangladesh. The river is navigable for 1,285 km/800 mi from the sea.