In the Tibet Autonomous Region there are some 20 rivers each with a drainage area of over 10,000 square km, and over 100 rivers with a drainage area of over 2,000 square km. The most important are the Jinshajiang, Nujiang, Lancangjiang and Yarlung Zangbo. The region is the source of some of the most famous rivers in Asia, such as the Ganges, Indus, Brahmaputra, Mekong, Salween and Irrawaddy.

The rolling Yalung Zangbo is the biggest river in Tibet, and the highest above sea level in the world. Originating in the Gyima Yangzong Glacier in Zhongba County at the northern foot of the Himalayas, it runs 2,057 km in China (ranking fifth in China in terms of length), draining an area of 240,480 square km (sixth in China). With the drainage area 4,500 meters above sea level, the Yarlung Zangbo is the highest river in the world. When it flows into India via Lhoyu, it is called the Brahmaputra River.

About 1 million people, or half of the population in the autonomous region, live in the area drained by the Yarlung Zangbo River with 153,333 hectares of cultivated land, or 50 percent of the Tibetan total. The area is also home to some major cities and towns, including Lhasa, Xigaze, Gyangze, Zetang, and Bayi.

The Yarlung Zangbo River turns to the northeast after Paiqu in Mainling, and makes a U-turn around Namjagbarwa, the highest peak in the eastern Himalayas to create the largest canyon in the world. The Yarlung Zangbo Grand Canyon is 5,382 meters deep, the deepest in the world. The river bottom is 74 meters at the narrowest part and 200 meters at the widest part, extending 370 km in length.