Tibet was home to part of the Himalayas.
The Second Doctor had previously visited Tibet in 1935 with Jamie McCrimmon and Victoria Waterfield, encountering the Great Intelligence for the first time. He also met a group of monks at the Det-Sen Monastery whom he helped to fight the Yeti of the Himalayas. (TV: The Abominable Snowmen)
K'anpo Rimpoche lived in Tibet for a time, learning the customs, the Tibetan language, and religion of that people. The Third Doctor also proved to be familiar with Tibetan customs. (TV: Planet of the Spiders)