Shortly afterwards it receives the Dibang, flowing from the northeast; but its principal confluent is the Dihong, which, deriving its origin, under the name of the Tsangpo, from a spot in the vicinity of the source of the Sutlej, flows in a direction precisely opposite to that river, and traversing the tableland of Tibet, at the back of the great Himalaya range, falls into the Brahmaputra in 27° 48' N.
Doubts were long entertained whether the Dihong could be justly regarded as the continuation of the Tsangpo, but these were practically set at rest by the voyage of F.
From Katmandu, the capital of Nepal, a difficult mountain route runs by Kirong to the No la (16,600 ft.), descending from which pass it strikes the Tsangpo about midway between Lhasa and Lake Manasarowar.
In the first, after an ineffectual attempt by Nepal, he travelled by the Manasarowar Lake, and the road thence eastward, parallel to the course of the Tsangpo, reaching Lhasa on the 10th of January 1866, and leaving it on the 21st of April 1867.
This watershed was found to lie much farther north than had been supposed, and to consist of very lofty mountains, in complicated ranges, from which large tributaries descend to the Tsangpo (Brahmaputra).