The Upper Mustang trek takes you into the hidden world of the old Buddhist Kingdom of Manang, which is also called Lo. LO used to be part of the Tibetan empire and is there for closely related to Tibet. Traditional Mustang (the Lo Kingdom) is 53 km north–south at its longest, 60 km east–west at its widest and ranges from a low point of 2,750 m above sea level on the Kali Gandaki River just north of Kagbeni to 6,700 m at Khamjung Himal, a peak in southeast Mustang.The main hydrographic feature of Mustang is the Gandaki River. The river runs southward towards Nepal Terai, bisecting Mustang. Routes paralleling the river once served as a major trade route between Tibet and India, especially for salt. Part of the river valley in the southern Mustang District forms the Kali Gandaki Gorge, by some measures the deepest gorge in the world. Upper Mustang is on an ancient trade route between Nepal and Tibet exploiting the lowest 4,660 metres (15,300 ft) passes Kora La through the Himalaya west of Sikkim. This route remained in use until China's annexation of Tibet in 1950.Mechanized access inside Nepal began with the opening of an airstrip at Jomsom at the approximate boundary between the southern Thak and northern Lo sections of the valley, which was in operation by the 1960s.
Upper Mustang is a restricted area and up till 1992 it was forbidden for foreign visitors to enter the kingdom. Nowadays foreigners are welcome to Upper Mustang for a permit fee of US$ 500 (to be arranged through a trekking agency and valid for 10 days, each additional day costs US$ 50).These days accommodation in guesthouses is possible along the whole trek. While staying there you are welcome to sit with the owners in the kitchen. In Tibetan culture the kitchen is the center of the house and built like a kind of living room. So there is no better way to learn a bit about the daily life than spending time in the kitchen! Trekking in Mustang is a great option during the monsoon months (June-August) as the region is in the rain shadow. However, it is best to add a day or two on each side of your itinerary for travel interruptions due to bad weather in the lowlands. While November is still a nice time to trek in Mustang keep in mind that seasonal migration takes place at this time and many residents from Lo Manthang and surrounding areas will move down to lower altitudes for the winter months. This may cause an inconvenience in restaurants and accommodation availability.