The Dibang originates near Keya pass on the Indo-Chinese border in the Dibang Valley district of Arunachal Pradesh. The drainage basin of the river within Arunachal Pradesh covers the districts of Dibang Valley and Lower Dibang Valley. The Mishmi Hills lie in the upper course of the Dibang which enters the plains at Bomjir, Dambuk etc. . Between Bomjir (Nizamghat) and Sadiya the Dibang has a steep river gradient and exhibits braided channel morphology with its width varying from . It often changes its course resulting in flooding and destruction of cultivable land and forests along its banks. The Dibang, with a total length of , enters the River Lohit north of the Dibru-Saikhowa sanctuary near the Assamese town of Sadiya.