Roopkund is a small glacial lake at about 5,000 m in the Garhwal Himalaya of Uttarakhand, India. When the ice melts for a few weeks each year, the shore shows leather shoes, glass bangles, bamboo staffs and the remains of several hundred people.

A forest ranger, H. K. Madhwal, reported the remains in 1942. During the war, officials first feared they might be Japanese soldiers, but the bones turned out to be far older.

In 2004, Subhash Walimbe of Deccan College described short, deep cracks on the tops of skulls, made by round objects about the size of cricket balls, and Oxford radiocarbon dates put the deaths at about 850 AD. The team concluded that giant hailstones had killed everyone at once. A local folk song also speaks of a goddess striking a royal pilgrimage with hail “hard as iron”.

Then a 2019 study in Nature Communications read genome-wide DNA from 38 individuals. It found at least three distinct groups: 23 people with South Asian ancestry who died between the 7th and 10th centuries, possibly in several events; 14 people with ancestry most like present-day people of Crete and Greece who died around 1800; and one person with ancestry more typical of Southeast Asia. The two main groups died roughly 1,000 years apart.

Hail is not ruled out for some of them, but one storm cannot explain deaths a millennium apart. As senior author Niraj Rai put it, “It is still not clear what brought these individuals to Roopkund Lake or how they died.”

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