Here’s what you’ll learn when you read this story:

• There had been rumors of skeletons at the bottom of India’s Roopkund Lake for centuries, but they were only confirmed by a park ranger who accidentally discovered bones nearby.
• Researchers who genetically analyzed the bones found that they belonged to two distinct genetic populations, an earlier South Asian group and a later Eastern Mediterranean group.
• How the Eastern Mediterranean Group, found to have originated on the Greek island of Crete, ended up there is still unknown, and more research is needed to find out.

The last vestige of a melted glacier, Roopkund Lake glitters like a sapphire set among the Himalayas. Located near near Uttarakhand, India, it has become a destination for hikers trekking through frozen terrain 16,500 feet (about 7,816 meters) above sea level. It’s a setting where Earth brushes the heavens, sacred to Hindus making the pilgrimage to the shrine of patron deity Nanda Devi, but when surrounding snows melt in the spring, they reveal something macabre.

Hari Kishan Madhwal had no idea what this breathtaking landscape was hiding. In 1942, the forest ranger was on patrol through Nanda Devi National Park when he crested a ridge and stopped cold. Human bones littered the shoreline of Roopkund Lake, jutting from the mud and glinting beneath its shallow waters. Some of these skeletons still had tatters of mummified flesh clinging to them. There had long been rumors of human remains in the lake since the 19th century, perhaps those of religious pilgrims or people in climbing expeditions passing between the foot of the Trishul and Nanda Ghunti mountains. But they were only stories, at least until Madwhal’s discovery. It soon came to be known as Skeleton Lake. Who were these unnamed people, and what phenomenon had left their remains in the lake?

Local legend has a ready answer, steeped in divine wrath. A king led a procession of revelers toward the shrine of the goddess Nanda Devi, but the party treated the pilgrimage as a festival—loud, lavish, and irreverent. The goddess took it as a desecration. She sent a tempest of iron balls screaming from the sky, and the entire group perished on the mountainside, their bodies left to the cold. A good story, but a story nonetheless.

In 2019, to find out the truth behind the legends, a team of researchers from Harvard University and the Max Planck Institute for the Science of Human History analyzed DNA from 38 of the 800 individuals whose remains were found at the lake. The results unearthed an even deeper mystery. It turned out that the skeletons belonged to two distinct genetic populations, and radiocarbon dating revealed they lived during different time periods, with the oldest dating to somewhere between 675 to 769 C.E. The others had perished around a thousand years later. An especially disturbing detail was that skulls in the earlier group showed signs of blunt force trauma to the head.

“Little is known about the origin of these skeletons, as they have never been subjected to systematic anthropological or archaeological scrutiny, in part due to the disturbed nature of the site, which is frequently affected by rockslides, and which is often visited by local pilgrims and hikers who have manipulated the skeletons and removed many of the artifacts,” the researchers said in a study published in Nature Communications.

Predictably, genetic evidence determined the oldest group to be South Asian, which is consistent with the population history of the region and implies there might be at least some truth to the legend about visitors to the shrine of a goddess. But instead of the onslaught of iron balls Nanda Devi is said to have unleashed on the revelers who were insufficiently solemn in their worship, the fractures in the skulls are now thought to have been caused by a brutal hailstorm.

Less explicably, however, the later group of skeletal remains was found to have originated in Eastern Mediterranean. Even stranger is that DNA testing revealed that these individuals were from Crete, a Mediterranean island near Greece that’s isolated from the mainland and thousands of miles from Lake Roopkund. It’s unlikely that these Cretans were religious pilgrims, since few Hindus were known to live there historically.

Further examination of carbon and nitrogen isotopes from femur collagen showed that the later group had a terrestrial diet, which is surprising for people from an island where fish and shellfish are a normal part of the diet. It’s therefore possible that these people came from an inland part of the island. Crete is mountainous, and in the past many more people used to live in its parched, forbidding mountains, herding sheep and goats and surviving on a diet of meat, milk and grain. These individuals were born at a time when Greece—including Crete—was ruled by the Ottoman Empire. But even to the researchers, it’s perplexing that people from inland Crete ended up in India; it’s unclear whether they were tourists, pilgrims, missionaries, or had some other purpose. Maybe they were escaping Ottoman rule under the guise of tourism. None of these potential explanations can be confirmed until more evidence emerges.

The scientific investigation hasn’t progressed any further despite the mysteries that linger, and the chance to study the remains in greater detail is dwindling. Bones have been moved around by hikers for photo ops and stuffed in suitcases to be taken home as grisly souvenirs. A definitive explanation for why the later group ended up at Roopkund Lake may be locked in their remains, or buried in the lake’s sediments, which thaw and become accessible for a narrow window once a year. Either way, no conclusion has been reached. The only thing we know for sure is that the deaths of the hundreds of individuals whose remains lie in this deceptively scenic but perilous place did not occur all at once.

“Given that the [later] individuals died only in the last few centuries, an important direction for future investigation will be to carry out archival research to determine if there were reports of large foreign traveling parties dying in the region over the last few hundred years,” said the researchers. “[But] taken together, these results have [still] produced meaningful insights about an enigmatic ancient site.”