The main feature of Mustang is the Kali Gandaki river, its valley and tributaries. It runs north-east to south-west towards Nepal Terai, bisecting the territory. The river was once the major trade route between Tibet and India, especially for salt. Part of the river valley, the Thak Khola, is the deepest gorge in the world. Most of the population of Mustang live near the river, 2-3,000 m above sea level, but the tough conditions cause a large seasonal migration into lower regions of Nepal. The administrative centre of the district is at Jomosom (Dzong Sampa), population 5363 (1998), which has had an airport since 1962 and has become the main tourist centre since the area was opened to tourism in the 1970s.
Mustang was once an independent kingdom, although closely tied by language and culture to Tibet. The monarchy still survives as the Kingdom of Lo in northern (Upper) Mustang, capital Lo Manthang, where the Raja (or Gyelpo) traces his lineage back to 1450 and Ame Pal, the warrior who created the Buddhist kingdom.