The Upper Mustang Trail, where tourists have been allowed to enter only since the 1990s, gave the trekking route another name: the Last Forbidden Kingdom. The Upper Mustang Trail offers a spectacular trekking experience in the remote trans-Himalayan mountain region of Nepal and is also a wonderful trek for any alpine hiker. Usually, the trek is done in eleven days, excluding travel days. The magnificent walk takes you slowly up the long Mustang Valley into one of the least traveled areas of Nepal along the ancient salt caravan route. The route provides tourists with stunning moonscape views across the expansive plateaus, and striking 8000-meter peaks await around every turn.

As the region is isolated from the outside world, it has a highly preserved Tibetan culture and unspoiled nature. Located in the rain shadow of the Dhaulagiri massif, creating a ruggedly arid land, the upper Mustang is surrounded by rocks of different colors and impressive formations. This desolate landscape is speckled with settlements of white-washed houses, barley fields, and chortens decorated with prayer flags, which add a splash of color to the landscape. The primary objective of the Upper Mustang trek is to reach the capital of Upper Mustang, Lo Manthang. Once you reach the pass Lo La (3950 m), the walled medieval capital in the distance is visible, with the white-washed 6-meter-tall wall sticking out in sharp contrast to the barren landscape. Trekkers feel overwhelmed with every step they take towards their destined location.
The optimum time for trekking in Mustang is during the monsoon season (June–August), since the region is located in the rain shadow.