The Sky Caves of Mustang

Across the cliffs of Upper Mustang, a high-altitude desert region of Nepal bordering Tibet, an estimated 10,000 caves have been carved into the soft conglomerate rock faces, some clustered in groups reaching up to 50 metres above the valley floor and accessible only via networks of footholds, ladders, and ropes — many caves have multiple storeys connected by internal staircases cut into the rock. The caves were largely unstudied by outside researchers until expeditions beginning in the early 2000s, led by archaeologists including Mark Aldenderfer, began systematically documenting their contents.

Excavations have recovered human skeletal remains radiocarbon-dated to as early as around 1000 BCE, some showing evidence of formal burial practices, alongside later Buddhist murals, painted clay sculptures, and illuminated manuscripts dating from around the 12th to 14th centuries CE — suggesting the caves served different purposes across different periods, including burial chambers, meditation retreats, granaries, and defensive refuges during conflicts between rival kingdoms in the region. Local oral tradition attributes the caves to the Khampa people fleeing earlier conflicts, or to ancient meditators seeking isolation, though archaeologists believe the full chronology likely involves multiple distinct waves of use by different groups over more than 2,000 years, with many caves still unexcavated and the full extent of the network not fully mapped.