For decades, experts puzzled over hundreds of ancient dead bodies found at a remote lake. Were they victims of disease? Mass suicide? War? The answer is weirder than you think.

For one month a year, the icy waters of Roopkund Lake melt enough to reveal scattered skeletal remains of 200 humans who perished in the region 1,200 years ago. Because of the harsh conditions of the remote lake, nestled 15,750 feet in the Himalayan mountains of India bordering Nepal and only accessible via a five-day ascending trek, scientists estimate there could still be 400 undiscovered bodies.

This grisly find was first uncovered by a British forest ranger in 1942, and immediately inspired legends to explain the identities of the mysterious group of dead trekkers. .........