The word "Chhu" means "river" or "water" in Dzongkha, the official national language in Bhutan.

The river rises in Gasa Dzongkhag (district) near the border between Bhutan and Tibet.

The confluence of the two streams is immediately below the Punakha Dzong, which is the winter home of the Dratshang Lhentshog (Central Monk Body) and the Je Khenpo.

After leaving Bhutan near the town of Lhamoidzingkha, formerly known as Kalikhola,[1] the river enters Assam in India and is known as the Sankosh.

The Sankosh ultimately empties into the Brahmaputra, flowing into the Bay of Bengal.