Researchers excavating an ancient ceremonial site in the Andes say the culture that thrived there engaged in violent, non-lethal rituals that led to lots of bloodletting.

Skeletal remains from the 13th century B.C. to the sixth century B.C. all bore appalling injuries. The researchers said it is the earliest evidence of ritual violence in a society in the American continent.

The site, Pacopampa, is in Peru’s northern highlands. Pacopampa was home to a complex society founded on ritual activity, according to an article published by the research team.

Tomohito Nagaoka, an associate professor of anthropology at St. Marianna University School of Medicine in Kanagawa Prefecture, took part in the excavation. The team's findings were published in the Sept. 28 online edition of U.S. scientific journal Plos One.

The researchers uncovered the remains of 104 individuals, seven of which bore significant physical injuries, such as fractured skulls, facial and limb fractures, and a dislocated elbow joint.

The evidence suggests that these individuals were repeatedly assaulted, but apparently not with sharp instruments.

An examination of the pelvises suggested that the victims were all aged 35 or older.

No signs of malnutrition were found.

There was evidence that severe bone fractures had been healed.

“Ancient records show that elite groups fought each other to ward off disaster and pray for good harvests,” said Yuji Seki, head of the Japan-Peru joint investigation team, and deputy director of the National Museum of Ethnology in Osaka Prefecture. He specializes in archaeology in the ancient Andes.

“These elite groups, such as oracles, might have repeatedly taken part in combat by throwing stones and using clubs,” Seki speculated.

Nagaoka stressed the importance of the findings, saying, “It is significant that we were able to examine the circumstances surrounding living, aging, illness and death of the ancient Andes people.”