Nepal's Cliffs Hide 10,000 Man-Made Caves — and No One Knows Who Built Them

Carved hundreds of feet up sheer desert cliffs, with no visible staircase and no written record of who built them, Upper Mustang's "sky caves" have been keeping secrets for at least 3,000 years. There are roughly 10,000 of them, stacked five storeys high in places, riddling the eroded cliffs of the Kali Gandaki valley — and archaeologists are still working out who dug them, and why.

The caves sit in Mustang District, Nepal's high desert kingdom on the Tibetan plateau's southern edge, in a landscape so dry and wind-carved it barely looks Nepali at all. Local legend says the caves once sheltered a demoness; more sober archaeology suggests they were built and rebuilt over roughly two millennia for at least three different purposes. Since the mid-1990s, when a joint Nepali–University of Cologne team began serious excavation, researchers have peeled back the layers: the oldest chambers, some cut as early as 1,000 BC, appear to have been burial sites; by the 10th century, during a period of regional conflict, similar caves were converted into defensible residential dwellings; by the 1400s, still others had become quiet meditation cells for Buddhist practitioners.

The 2008 finds were especially striking: manuscripts blending Buddhist and older Bon religious texts, painted 12th–14th century Buddhist artwork, and skeletons packed into chambers that were clearly built for the dead, not the living. Two years later, a joint climbing-and-archaeology team working near Samdzong pulled 27 human remains from a single cluster of caves, many bearing cut marks consistent with sky burial — a practice of preparing bodies on high, exposed ground rather than burying them in the ground, still used in parts of the Tibetan Buddhist world today.

What nobody has fully answered is the engineering question: how a pre-industrial society cut multi-storey chambers with internal ladders and connecting shafts into vertical cliff faces hundreds of feet above the valley floor, with no scaffolding and no modern tools. Some rooms clearly stored grain and water; others were living quarters; others were tombs. The builders left no inscriptions explaining themselves, and Mustang's isolation — it was a restricted area closed to outsiders until 1992 — means the caves went largely unstudied by the outside world until remarkably recently.

Ten thousand caves, three thousand years, and a civilization that left its dead — and its questions — hanging in the cliffs. Mustang remains one of the least-visited, most archaeologically strange corners of Nepal, and the sky caves are the reason why.

Source: Wikipedia — Mustang Caves

Cover photo: Rajan Pun via Pexels (Pexels License).