Which eight-thousander is the only one entirely in Tibet?

Shishapangma is the only eight-thousander entirely in Tibet.

Also called Xixabangma or Gosainthan, it rises to 8,027 metres in south-central Tibet, near the Nepal border. It is the world's 14th-highest mountain and the lowest of the eight-thousanders by elevation.

The mountain lies in the Jugal Himal, a Himalayan subrange often linked with Nepal's Langtang Himal. Unlike several other eight-thousanders near international borders, Shishapangma's entire massif is on the Tibetan side. Cho Oyu, by contrast, straddles the Tibet–Nepal border, making it a common mix-up.

A Chinese expedition made the first ascent on 2 May 1964. Climbers also distinguish the true summit from Shishapangma's lower central and western summits; reaching the highest point requires traversing a potentially difficult summit ridge.