The Brahmaputra is considered to be among the most majestic rivers in the world. The Brahmaputra enters India in the state of Arunachal Pradesh, 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 35 km (22 mi) and 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, enters the state of Assam, and becomes very wide—as wide as 10 km (6 mi) in parts of Assam.