Nestled in the Indian Himalayas, some 16,500 feet above sea level, sits Roopkund Lake. One hundred and thirty feet wide, it is frozen for much of the year, a frosty pond in a lonely, snowbound valley. But on warmer days, it delivers a macabre performance, as hundreds of human skeletons, some with flesh still attached, emerge from what has become known as Skeleton Lake.

Who were these individuals, and what befell them? One leading idea was that they died simultaneously in a catastrophic event more than 1,000 years ago. An unpublished anthropological survey from several years ago studied five skeletons and estimated they were 1,200 years old.

But a new genetic analysis carried out by scientists in India, America and Germany has upended that theory. The study, which examined DNA from 38 remains, indicates that there wasn’t just one mass dumping of the dead, but several, spread over a millennium.

The report, published Tuesday in Nature Communications, has led to a “far richer view into the possible histories of this site” than previous efforts provided, said Jennifer Raff, a geneticist and anthropologist at the University of Kansas who was not involved with the work.