An impressive set of more than 400 human footprints found around an African volcano has been determined by researchers to date back between 5,000 and 19,100 years ago.

The footprints were found in the mudflats in the shadow of the Ol Doinyo Lengai volcano in Tanzania, reports National Geographic. No other site in Africa has as many Homo sapiens footprints.

Some of the steps appear to show that people were walking very briskly, even jogging, going as fast as a 12-minute mile. Some tracks implied that women and children seemed to be traveling in large groups together. And in at least one instance, one set of steps showed that someone was possibly walking with a broken toe.

“The first time we went out there, I remember getting out of the vehicle, and I teared up a little bit,” Cynthia Liutkus-Pierce, the Appalachian State University geologist who led the research, told National Geographic. “Human origins is a huge interest of mine: where we came from, and why we are who we are. It was definitely emotional to see our own history in this.”

Researchers think that mud rich with ash likely washed off Ol Doinyo Lengai, heading downhill to form the mudflats. In the hours to days before the mud dried, it preserved the prints in the cracked crust. But the researchers think another flow buried the footprints at least 10,000 to 12,000 years ago, covering them up.

Originally, the researchers thought that the mudflats were created when the volcano erupted and sent ash raining down, making them believe the prints could be 120,000 years old. They now believe the ash was delivered by water, which would date the prints as much younger.

A local villager had found some of the prints in 2006, but scientists didn't find out about the site until 2008. They've only recently published their findings after years of studying and dating the tracks.

Now that the time frame has been pinpointed, the researchers are working on finding out more about the lives of these early humans.

“It’s a very complicated site,” William Harcourt-Smith, a paleoanthropologist at the City University of New York and a member of the research team, told National Geographic. “There’s one area where there are so many prints, we’ve nicknamed it the ‘dance hall,’ because I’ve never seen so many prints in one place. It’s completely nuts.”

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.