Archaeologists have discovered dozens of tombs on a 1,200-year-old ceremonial site in Peru. Each tomb contains up to 40 mummies, from fetuses and older adults.

The team, consisting of over 30 people from Peru, the U.S., Canada and Sweden, has excavated 171 mummies so far from seven tombs in Tenahaha, doing so between 2004 and 2007. The remains were not in good condition due to water damage and rodents that could have been feeding on them. The researchers also noticed that some tombs have broken remains.

Using radiocarbon dating analysis, the archaeologists determined that the site was built between A.D. 800 and A.D. 1000. During this time, Peru was undergoing a series of changes such a population boom, agricultural expansion, and class differences. However, the way the mummies were stored in the tombs indicated that the civilization was a community of equals despite having multiple leaders, according to LiveScience.

"Though many individuals were broken apart, others were left intact," archaeologist Justin Jennings, a curator at Toronto's Royal Ontario Museum, wrote in a chapter of the newly published book "Tenahaha and the Wari State: A View of the Middle Horizon from the Cotahuasi Valley." "People were moved around the tombs, but they sometimes remained bunched together, and even earth or rocks were used to separate some groups and individuals."

It also seemed that the residents of ancient Tenahaha lived peacefully based on the pottery excavated on site, which contains images of smiling faces. The archaeologists concluded that the site could have been used as a common ground for burying the dead, as well as for celebrations.

"It's a period of great change and one of the ways which humans around the world deal with that is through violence," Jennings said in the interview with LiveScience. "What we are suggesting is that Tenahaha was placed in part to deal with those changes, to find a way outside of violence, to deal with periods of radical cultural change."