From Quora, a pretty interesting story.
In 1942, H K. Madhawl, a British forest guard in Roopkund, India made an alarming discovery (despite the fact that there had been reports of bones on the lake shore since the mid 19th century). At an elevation of 15,750 feet, near the bottom of a small valley, was a frozen lake absolutely full of skeletons. Roopkund Lake, in the state of Uttarakhand, India, was a six-foot-deep glacial lake that typically remained frozen year round.
What he saw up there confused everyone. At first, it was one bone. But as the temperatures rose, the number of exposed remains grew exponentially. That summer, the ice melting revealed even more skeletal remains, floating in the water and lying haphazardly around the lakeâ€™s edges. People wondered what happened, and what were these people doing up here?
The immediate assumption (it being war time) was that these were the remains of Japanese soldiers who had died of exposure while sneaking through India. The British government, terrified of a Japanese land invasion, sent a team of investigators to determine if this was true. However upon examination they realized these bones were not from Japanese soldiersâ€”they werenâ€™t new enough.
With the immediate concerns of war eased, the urgency of identifying the remains became less of a priority and efforts to further analyze the remains were sidelined. It was evident that the bones were quite old indeed. Flesh, hair, and the bones themselves had been preserved by the dry, cold air, but no one could properly determine exactly when they were from. More than that, they had no idea what had killed over 300 people in this small valley. Many theories were put forth including an epidemic, landslide, and ritual suicide. For decades, no one was able to shed light on the mystery of Skeleton Lake.
But what caused their death? Was there a massive landslide? Did some disease strike suddenly? Were the individuals conducting a ritualistic suicide? Did they die of starvation? Were they killed in an enemy attack? One theory even suggests that the individuals did not die at the scene of the lake, but their bodies were deposited there as a result of glacial movement.
A 2004 expedition to the site seems to have finally revealed the mystery of what caused those peopleâ€™s deaths. The answer was stranger than anyone had guessed.
The 2004 expedition took samples of the bones as well as bits of preserved human tissues. As it turns out, all the bodies date to around 850 AD.
DNA evidence indicates that there were two distinct groups of people, one a family or tribe of closely related individuals, and a second smaller, shorter group of locals, likely hired as porters and guides. A number of these victims of the mountain were so well preserved that they still had remnants of flesh, hair, fingernails, and clothes. Rings, spears, leather shoes, and bamboo staves were found, leading experts to believe that the group was comprised of pilgrims heading through the valley with the help of the locals.
The plausible scenario of what exactly happened? The two groups perhaps met at the foot of the mountain. The first of the two, taller and who which outnumbered the others, probably wanted to make a pilgrimage pass through the mountain and are thought to have been of Iranian origin. The second group, with thinner and smaller bones, showed up as their local Indian guides. The travelers were related to each other (a large family or tribe), and could have come from Iran. The locals that guided the way were unrelated.
Another suggestion is that they braved the elements to collect â€œKeeda Jadi,â€ which are larvae of the ghost moth that have become the home to a fungus (that actually wraps around the larvae and slowly devours it).
These â€œMagical Mushroomsâ€ are believed to have incredible medicinal properties and locals head out in search of them in the springtime.
The journey should have progressed well until the point everyone was trapped, with no place to run and hide as a disaster struck. A violent torrent of baseball-sized hailstones falling from the skies battered the whole group. All the bodies had died in a similar way, from blows to the head. However, the short deep cracks in the skulls appeared to be the result not of weapons, but rather of something rounded. The bodies also only had wounds on their heads, and shoulders as if the blows had all come from directly above. What had killed them all, porter and pilgrim alike?
Among Himalayan women there is an ancient and traditional folk song. The lyrics state that â€œthese are the holy lands of the Goddess Nanda, her sanctuary in the mountains. King Jasdal of Kanauj and his wife were undertaking the â€œNanda Jatâ€ pilgrimage; along the way, the queen gave birth. Instead of pleasing their goddess with their tributes, the deity was angered for this defielment of her pure mountain. To punish the group, she sent a great snowstorm, flinging iron-like hailstones that took the life of each and every personâ€.
After much research and consideration, the 2004 expedition came to the same conclusion. All 300 people died from a sudden and severe hailstorm. Trapped in the valley with nowhere to hide or seek shelter, the â€œhard as ironâ€ cricket ball-sized [about 23 centimeter/9 inches circumference] hailstones came by the thousands, resulting in the travelersâ€™ bizarre sudden death. The remains lay in the lake for 1,200 years until their discovery.