A roughly 4,000-year-old burial site discovered on an island off the coast of Georgia points toward ties between early hunter-gatherers living on opposite sides of North America.

As researchers led by Matthew Sanger, an anthropologist at New York’s Binghamton University, report in the journal American Antiquity, the McQueen shell ring—a large circle of shells centered around a burial pit filled with stone tools, the cremated remains of seven humans and a ceremonial copper band—closely mirrors graves seen in the Great Lakes region, suggesting ancient humans from what is now the United States’ Upper Midwest spread their funerary practices via direct contact with distant communities.

The team’s latest findings build on a study published in the Journal of Archaeological Science: Reports this past April. Per the paper, an elemental analysis of the copper band found on St. Catherines Island off the coast of Georgia pinpointed its origins to copper mines near Lake Superior, where similar copper objects appear in connection with early burials.

According to Science News’ Bruce Bower, the research indicates that envoys, traders or religious pilgrims from Lake Superior traveled more than 900 miles to St. Catherines, a small patch of land situated around 20 miles from Savannah.

Previously, Sanger tells Bower, “There was no clear evidence for direct, long-distance exchange among ancient hunter-gatherers in eastern North America.”

Although, the authors of the new study acknowledge that it is “difficult to determine the origin point(s) of the various mortuary practices found” at the shell ring, they note that parallels between practices seen in the far-flung regions, in addition to the copper’s proven provenance, suggest the emergence of “vast social networks thousands of years earlier than typically assumed.”

Writing for Ars Technica in July 2018, science journalist Kiona N. Smith explained that shell rings are common burial features in what is now the southeastern U.S. But the McQueen shell ring differs from neighboring grave sites in several ways: It is only the second coastal shell ring to yield a copper artifact (the other is in Poverty Point, Louisiana), and it reveals evidence of cremation—a practice rarely seen in the region.

Crucially, Bower explains for Science News, the fact that St. Catherines’ inhabitants directly followed rituals established by hunter-gatherers in the Midwest differentiates the exchange from those more commonly believed to characterize early North Americans’ interactions. Experts estimate that local populations started trading stone tools and other goods around 5,000 years ago, relying on a cascading string of exchanges between neighboring communities to slowly spread items further afield. With this decidedly indirect method, the original hunter-gatherers responsible for initiating trade had no influence on how later recipients wielded the objects at hand; when trade became more direct, however, rituals and objects were passed along with few changes.

Researchers have traditionally dated the advent of long-distance direct exchange to 2,000 years ago, but as Sanger and his colleagues note, the McQueen shell ring could place this practice’s emergence closer to 4,000 years ago. The impetus for such interactions, the team writes, may have been seasonal gatherings designed to join communities both nearby and further afield. According to Archaeology, individuals from the Southeast and the Great Lakes region could have assembled at St. Catherines for sumptuous ceremonies involving ritualistic funerals and feasts of fish, clams, oysters, hickory nuts and acorns.