The Dibang river flows through the Indian state of Arunachal Pradesh through its middle course across the Lower Dibang Valley district of Arunachal Pradesh. The Dibang river is an important tributary of Brahmaputra. The Dibang river and Lohit river merge together and flow along the northern side of the Saikhowa reserve forest. The Mishmi Hills is found along the upper courses of the Dibang river.  

The demographic area type of Dibang River Valley is hydrographic. The region all along the upper courses of the river is located in the Great Himalayan Mountain range, with its northern and eastern reaches boarding Tibet. The Mishmi Hills is the southward expansion of the Himalayas; compose most of the northern part of the region. They have an average elevation of 15,000 feet (4,5000 m) and area dotted with passes such as Yonggyap at 13,000 fee (3,950 m) and Kaya at 15,600 feet (4,750 m). The Dibang along with other rivers like Ahui, Adzon, Emra, and Dri streams flow southward to join Brahmaputra River.