The Nyamjang Chu river originates in the snow-clad peaks of the eastern Himalayas, north of Taga in the Chudromo township of the Tsona County, at an elevation of 5,400 m (17,700 ft).

[5][6] From this location, Nyamjang Chu flows southwards for about 85 kilometres (53 mi) in Tibet,[1] passing by several towns such as Chudromo, Dongkar, Gongri, Kyipa, Marmang and Le.

South of Le (also spelt Lei and Lai), the river enters India at a location called Khinzemane at an elevation of 2,220 m (7,280 ft).

[8] The river flows mostly southwards in India for 40 km and joins the west-flowing Tawang Chu near Lumla.

[1] The Zemithang valley is one of the wintering locations for the black-necked crane, a vulnerable species of which only 4,000 are believed to be alive as of 1996.