An archeological dig in Brookfield has yielded Native American burial mounds datingas far back as 1,000 BC, researchers said.

The remains, found at the Tobin Campground, belong to the Adena people, a group of Native Americans who mostly lived hundreds of miles away in the Ohio River valley.The Adena were among the first to bury their dead in elaborate burial mounds, according to Eric Johnson, director of Archeological Services at the University of Massachusetts Amherst.

Johnson called the site “historically significant’’ because it givesresearchers a glimpse into Adenaculture and how they may have come to New England. “It was first believed that people may have migrated from elsewhere. But now we think that artifacts crossed across multiple cultural groups in trade,’’ Johnson said. “The goal of this dig was not to remove anything from the campground, but rather to identify Adena remains so that the site could be registered and preserved under the National Register of Historic Places,’’ he said.

“We didn’t actually dig up that much dirt or any artifacts. Our aim was to dig long, but very shallow, trenches to remove the topsoil that had gathered over the site to look at what was underneath, but not disturb it. That way we maintain the integrity of the site,’’ he said.

Johnson said that while the two-week dig found “intact features of Adena origin,’’ the archeologists will have a difficult time distinguishing a grave from a refuse pile. “It’s hard to find graves with discernible human remains that are that old. Things deteriorate, but we know there were people here and people bury their dead,’’ he said.

According to Johnson, this dig is not the campground’s first. In the 1960s, an amateur archeologist uncovered native graves with human remains and removed them, he said. It was in partbecause of that incident the town of Brookfield used a grant from the Massachusetts Historical Commission to pay for the most recent dig, Johnson said.

He added that the members of the Chaubunagungamaug Nipmuck tribe worked with the archeologists to ensure that, should any human remains be found, they be treated carefully and with respect.

Johnson hopes that, once the campground is recognized as a historical site, it can become a place where people learn about history andNative American culture.

“This is a significant site,’’ he said. “We’re working to make sure that it becomes a place of education and remains undisturbed. There are people here and they need to be protected.’’

Andrew Grant can be reached at andrew.grant@globe.com.