Mo Chhu is a major river in Bhutan

Bhutan

Bhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...

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

Gasa District

Gasa District or Gasa Dzongkhag is one of the 20 dzongkhags comprising Bhutan. Its capital is Gasa Dzong near Gasa. It is located in the far north of the county and spans the Middle and High Himalayas. The dominant language of the district is Dzongkha, the national language...

 (district) near the border between Bhutan and Tibet. From there, the Mo Chhu flows generally southward to Punakha

Punakha

thumb|right|Punakha Dzong and the [[Mo Chhu]]Punakha is the administrative centre of Punakha dzongkhag, one of the 20 districts of Bhutan. Punakha was the capital of Bhutan and the seat of government until 1955, when the capital was moved to Thimphu. It is about 72 km away from Thimphu and it...

 in central Bhutan, where it joins the Pho Chhu from the northeast. The confluence of the two streams is immediately below the Punakha Dzong

Punakha Dzong

The Punakha Dzong, also known as Pungtang Dechen Photrang Dzong is the administrative centre of Punakha dzongkhag in Punakha, Bhutan. Constructed by Zhabdrung Ngawang Namgyal in 1637–38, it is the second oldest and second largest dzong in Bhutan and one of its most majestic structures...

, which is the winter home of the Dratshang Lhentshog

Dratshang Lhentshog

The Dratshang Lhentshog is the Commission for the Monastic Affairs of Bhutan. Under the 2008 Constitution, it is the bureaucracy that oversees the Drukpa Kagyu sect that is the state religion of Bhutan...

 (Central Monk Body) and the Je Khenpo

Je Khenpo

The Je Khenpo , formerly called the Dharma Raj by orientalists, is the title given to the senior religious hierarch of Bhutan. His primary duty is to lead the Dratshang Lhentshog of Bhutan, which oversees the Central Monastic Body, and to arbitrate on matters of doctrine, assisted by lopons...

.
The combined streams are then joined by the Dang Chhu near the town of Wangdue Phodrang

Wangdue Phodrang

Wangdue Phodrang District is a dzongkhag of central Bhutan. This is also the name of the dzong which dominates the district, and the name of the small market town outside the gates of the dzong...

, and the name of the river becomes the Puna Tsang Chhu. The river then flows through Dagana

Dagana District

Dagana District is one of the 20 dzongkhag comprising Bhutan...

 and Tsirang District

Tsirang District

Tsirang District , is one of the 20 dzongkhags of Bhutan. The administrative center of the district is Damphu...

s. After leaving Bhutan near the town of Kalikhola

Kalikhola

Kalikhola is a village development committee in the Himalayas of Taplejung District in the Mechi Zone of north-eastern Nepal. At the time of the 1991 Nepal census it had a population of 730.-External links:*...

, the river enters Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

 in India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 and is known as the Sankosh

Sankosh

Sankosh is a river that rises in northern Bhutan and empties into the Brahmaputra in the state of Assam in India. In Bhutan, it is known as the Puna Tsang Chu below the confluences of several tributaries near the town of Wangdue Phodrang. The two largest tributaries are the Mo Chhu and Pho...

. The Sankosh ultimately empties into the Brahmaputra.