Situated at over 5,000 meters above sea level in the Himalayan Mountains, Roopkund Lake is home to the scattered skeletal remains of several hundred individuals of unknown origin. We report genome-wide ancient DNA for 38 skeletons from Roopkund Lake, and find that they cluster into three distinct groups. A group of 23 individuals have ancestry that falls within the range of variation of present-day South Asians. A further 14 have ancestry typical of the eastern Mediterranean. We also identify one individual with Southeast Asian-related ancestry. Radiocarbon dating indicates that these remains were not deposited simultaneously. Instead, all of the individuals with South Asian-related ancestry date to ~800 CE (but with evidence of being deposited in more than one event), while all other individuals date to ~1800 CE. These differences are also reflected in stable isotope measurements, which reveal a distinct dietary profile for the two main groups.

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The Roopkund_B cluster is more puzzling. It is tempting to hypothesize that the Roopkund_B individuals descend from Indo-Greek populations established after the time of Alexander the Great, who may have contributed ancestry to some present-day groups like the Kalash21. However, this is unlikely, as such a group would be expected to have admixture with groups with more typical South Asian ancestry (as the Kalash do), or would be expected to be inbred and to have relatively low genetic diversity. However, the Roopkund_B individuals have evidence for neither pattern (Supplementary Note 9). Combining different lines of evidence, the data suggest instead that what we have sampled is a group of unrelated men and women who were born in the eastern Mediterranean during the period of Ottoman political control. As suggested by their consumption of a predominantly terrestrial, rather than marine-based diet, they may have lived in an inland location, eventually traveling to and dying in the Himalayas. Whether they were participating in a pilgrimage, or were drawn to Roopkund Lake for other reasons, is a mystery. It would be surprising for a Hindu pilgrimage to be practiced by a large group of travelers from the eastern Mediterranean where Hindu practices have not been common; Hindu practice in this time might be more plausible for a southeast Asian individual with an ancestry type like that seen in the Roopkund_C individual. Given that the Roopkund_B and Roopkund_C 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.

https://www.nature.com/articles/s41467-019-11357-9