The river originates from West Khasi Hills of Meghalaya.

After travelling 12 km in Meghalaya, the river then flows through Kamrup district of Assam and is known as Kulsi.

The confluence of the Kulsi with Brahmaputra River is at Nagarbera of Kamrup district, Assam.

This endangered dolphin (known as Xihu in Assamese language) breeds only in the Subansiri and Kulsi rivers across the entire Brahmaputra delta.

[1] However, sand mining and other development activities make dolphins in the Kulsi vulnerable and the numbers of this endangered dolphin have sharply declined.