Upper Mustang was restricted area until 1992; it is one of the most preserved regions in the world due to its hidden isolated nature from the modern world, having the majority of the population still speaking traditional Tibetan Languages. Mustang is driven from the Tibetan word 'plain of aspiration' which was opened to foreigners after 1992. It is one of the popular trekking routes of Nepal. The territory of Upper Mustang remained isolated from the 14th century. 
The entire area of Mustang is included in the Annapurna Conservation Area.