The Kali Gandaki River has carved the deepest river canyon in the world between Dhaulagiri (8 167 m) and Annapurna (8 091 m). Mustang, the former Buddhist Kingdom of Lo, is one of many small kingdoms that used to extend along the upper Kali Gandaki. Set amidst the majestic scenery of the Tibetan Plateau are ancient forts, walled medieval villages and monasteries rich with Buddhist art. Surrounded by Tibet on three sides, Mustang is an enclave of traditional Tibetan culture untouched by the Chinese occupation. Despite their isolation, the people of Mustang are worldly, well-traveled and resourceful. Essentially Tibetans, they are skillful traders, travelers and merchants and are by no means a primitive tribe that needs to be protected from outside influence. Lo, or Mustang, maintained its statues as a separate principality with a Raja until 1951 when it was incorporated into Nepal.
Only in 1992 did the Nepal government allow the first groups to enter Mustang. Each westerner must pay a special permit costing $500 for the first 10 days and $70 for each additional day spent in Mustang. A total of 400 westerners are allowed to enter Mustang per year. Therefore, the special permit results in a more expensive trek cost per day than other treks.
The trek to Mustang is through an almost treeless barren landscape. Strong winds generally howl across the area in the afternoon, generally subsiding at night. Being in the rain shadow of the Himalaya, Mustang has much less rain than the rest of Nepal although the skies are often cloudy during the monsoon season and rain sometimes occurs. Villages are several hours apart and appear in the distance almost as mirages. After the crops are planted, there are green oasises in the desert-like landscape of endless expanse of yellow and gray rolling hills eroded by wind. - See more at: http://traveltimes.com.np/package/nepal/Upper-Mustang-Lodge-Trek#sthash.zftyCXMy.dpuf