The Yarlung Tsangpo enters the state of Arunachal Pradesh in India, where it is called Siang. It makes a very rapid descent from its original height in Tibet and finally appears in the plains, where it is called Dihang. It flows for about southward after which, it is joined by the Dibang River and the Lohit River at the head of the Assam Valley. Below the Lohit, the river is called Brahmaputra and Doima (mother of water) and Burlung-Buthur by native Bodo tribals, it then enters the state of Assam, and becomes very wide—as wide as in parts of Assam.