Located north of Annapurna and at an average altitude of 4,000m, Mustang is geologically and culturally part of the Tibetan plateau. This old Buddhist kingdom, also called Lo, used to be part of the Tibetan empire. It became independent in 1380 and the Kingdom prospered due to its strategic location controlling the trade between Tibet, Nepal and India. The walled city of Lo Mangthang became the capital where the last king resided until 2016 in his 4 story high palace. Mustang was annexed by Nepal in 1946 and in the early 1960s; it was the hotbed for the Khampa guerrillas fighting the Chinese forces in Tibet. The USA supported these fighters and secretly trained some of them.