Mustang is one of the eleven districts of Gandaki Province and one of seventy-seven districts of Nepal. It covers an area of 3,573 km² (1,380 sq mi) and has a population (2011) of 13,452. The headquarters is located at Jomsom. Mustang is the 5th largest district (by area) of Nepal.

The district is a part of Gandaki Province in northern Nepal, straddles the Himalayas and extends northward onto the Tibetan Plateau. The district is one of the remotest areas in Nepal and is second in terms of the sparsity of population.The elevation ranges from 1,372 to 8,167 meters (Mount Dhaulagiri, the 7th highest mountain in the world), with several peaks above 7,000 meters.

Mustang was an ancient forbidden kingdom, bordered by the Tibetan Plateau and sheltered by some of world’s tallest peaks, including 8000-meter tall Annapurna and Dhaulagiri. Strict regulations of tourists here have aided in maintaining Tibetan traditions.Upper Mustang was a restricted demilitarized area until 1992, which makes it one of the most preserved regions in the world due to its relative isolation from the outside world, with a majority of the population still speaking traditional Tibetic languages.The name “Mustang” is derived from the Tibetan word meaning, “Plain of Aspiration.” Upper Mustang was only opened to foreigners in 1992 (annual quota at present of 1,000 people). It is a popular area for trekking and can be visited year round (regardless of season).

Mustang, the second least populated district of Nepal, is flanked by the Nepalese districts of Manang, the least populated, to the east and Dolpa, the third least populated, to the west. The Tibetan frontier stretches north from Mustang’s borders. Mustang is divided into two sub-regions, Lower and Upper.This is a high-altitude trans-Himalayan region spread over 3,640 square kilometres in area barely north of the main Himalayan mountain range. Geographically this cold high-altitude steppe is a part of the Tibetan highlands. This boot-shaped piece of land thrusts north into western Tibet is caught in the rain shadow of Dhaulagiri to the south and west and the Annapurna Massif to the north and east.

Average elevation of Mustang is 13,200 ft (2,500m), coming to a peak at 8,167m — the summit of Dhaulagiri. It is a vast and arid valley, distinguished by eroded canyons, vividly coloured stratified rock formations and barren high-altitude deserts.The area receives an average annual rainfall of less than 260 mm at Jomsom in the Lower Mustang. Spring and autumn are generally dry, but some precipitation is brought by summer monsoons, which averaged 133 mm at Jomsom between 1973 and 2000. The mean minimum monthly air temperature falls to -2.7 °C in winter while the maximum monthly air temperature reaches 23.1 °C in summer. Both diurnal and annual variations in temperature are large. Only about 40.3 square kilometers, about 1 percent of the total land area, is cultivated and 1,477 square kilometers, about 40%, is pasture land. Kora La at 4,660 metres (15,290 ft) in elevation is considered the lowest drivable path between Tibetan Plateau and Indian subcontinent.

The elevation of the district range from 1640m in nearby Kopchepani under Kunjo VDC to 7061m in Nilgiri North above from the sea level. The peaks above 6000m in Mustang District are Tukuche peak (6920m), Nilgiri South (6839m), Yakwakang Peak (6462m), and Damodar Himal (6004m). Thorung Pass (5416m), arguably the world’s highest and busiest pass, is located in this district. This district share 134.16 km (83.36 mi) long international border with Tibet Autonomous Region of China where 16 boundary pillars are in existence from pillar no. 18–33.