The Brahmaputra is a trans-boundary river and one of the major rivers of Asia. It is also called the Yarlung Tsangpo River .

From its origin in southwestern Tibet as the Yarlung Tsangpo River, it flows across southern Tibet to break through the Himalayas in great gorges and into Arunachal Pradesh where it is known as Dihang. It flows southwest through the Assam Valley as Brahmaputra and south through Bangladesh as the Jamuna. There it merges with the Ganga to form a vast delta. About 1,800 mi (2,900 km) long, the river is an important source for irrigation and transportation. Its upper course was long unknown, and its identity with the Yarlung Tsangpo was only established by exploration in 1884-86. This river is often called Tsangpo-Brahmaputra river.

While most Indian and Bangladeshi rivers bear female names, this river has a rare male name, as it means "son of Brahma" in Sanskrit.

As the river enters Arunachal Pradesh, it is called Siang and makes a very rapid descend from its original height in Tibet, and finally appears in the plains, where it is called Dihang. It flows for about 35 km and is joined by two other major rivers: Dibang and Lohit. From this point of confluence, the river becomes very wide and is called Brahmaputra. It is joined in Sonitpur District by the Jia Bhoreli (named the Kameng River where it flows from Arunachal Pradesh) and flows through the entire stretch of Assam. In Assam the river is sometimes as wide as 10 km. Between Dibrugarh and Lakhimpur districts the river divides into two channels---the northern Kherkutia channel and the southern Brahmaputra channel. The two channels join again about 100 km downstream forming the Majuli island. At Guwahati near the ancient pilgrimage centre of Hajo, the Brahmaputra cuts through the rocks of the Shillong Plateau, and is at its narrowest at 1 km bank-to-bank. Because the Brahmaputra is the narrowest at this point the Battle of Saraighat was fought here. The first rail-cum-road bridge across the Brahmaputra was opened to traffic in April 1962 at Saraighat.

The old Sanskrit name for the river is Lauhitya and the local name in Assam is Luit. The native inhabitants, i.e., the Bodos called the river Bhullam-buthur, which means 'making a gurgling sound', later Sanskritized into Brahmaputra.