The Himalayas contain many unique and ancient cultures. Recently, a team of researchers and mountaineers led by archaeologist Dr. Mark Aldenderfer began unraveling mysteries surrounding peoples who lived thousands of years ago in the caves of Nepal's Upper Mustang region.

Aldenderfer led a 20-day expedition to the Upper Mustang to explore mysterious communal graves discovered in the 1990s. The skeletons and burial artifacts were found in caves on the sides of cliffs. To identify possible burial sites, Aldenderfer and his team, including bioarchaeologist Dr. Jackie Eng and seven-time Everest climber Pete Athans, combed the region for deep caves on the brink of collapse. The bones that Aldenderfer's team collected, thought to be the mysterious Membrak people, were then cleaned, pieced together, and analyzed.

Cave burials are common in both the Upper and Lower Mustang regions, but there are differences in burial rituals. Not only is there a difference in burial rituals between the Upper and Lower Mustang regions, but between the Upper Mustang region and everywhere else in the world. People of the Upper Mustang practice de-fleshing as a key part of the procedure, in order to expedite the spirits of the dead to the next world.

This is a true vérité scene, where the camera candidly records a rare moment of discovery: bioarchaeologist Dr. Jackie Eng and archaeologist Dr. Mark Aldenderfer discover cut marks on the bones of the early Samdzong people of Upper Mustang, Nepal.

In this clip, we see the painstaking process by which Eng finds the cut marks. She cleans the bones with a toothbrush-like instrument. Because she's in a remote location, she doesn't have a microscope. Still, to an experienced scientist like Eng, the indentations are clearly cut marks made with a bladed instrument. These cut marks indicate de-fleshing as part of the Samdzong burial ritual.

Eng must count the number of marks on each bone, as well as where they are located and the type of mark. She must also have photographer and alpinist Cory Richards photograph each mark for documentation and later analysis. Only then will she truly feel comfortable calling the cut marks evidence of a practice of de-fleshing.

What else could it be? Jackie needs to rule out murder and cannibalism among other mortuary practices. But in the end, she determines the practice was definitely post-mortem de-fleshing of the bones. Another term for de-fleshing is excarnation.