A fresh group of ancient hunter-gatherers has been recognized by scientists. They resided close to the land bridge connecting North America and South America approximately 6,000 years ago.

Researchers are still charting how human populations spread across the Americas thousands of years ago, arriving first in North America before veering south. Groups that split off developed their own collection of genes that scientists can use to piece together the human family tree.

Discovered through ancient DNA, the group lived in the high plateaus of present-day Bogotá, Colombia — close to where the Americas meet. Scientists aren’t sure exactly where they fall in the family tree because they’re not closely related to ancient Native Americans in North America and also not linked to ancient or present-day South Americans.

The new study was published Wednesday in the journal Science Advances.

“Up to this point, we didn’t believe there was any other lineage that would appear in South America,” said archaeologist Andre Luiz Campelo dos Santos with Florida Atlantic University who was not involved with the new research. “This is unexpected.”

Just 4,000 years later, these ancient humans were gone and a genetically-different human clan inhabited the area. Scientists aren’t sure exactly what happened to make them fade away — whether they mixed into a new, bigger group or were pushed out entirely.

Analyzing more genes in South America will help confirm if this new group truly did disappear or if there could be evidence of their descendants elsewhere, said Campelo dos Santos.

Studying these ancient Colombian genes are important to piecing together the history of the Americas since ancient people had to cross this land bridge to settle in and spread across South America.

The area is “the gateway to the South American continent,” said study author Andrea Casas-Vargas with the National University of Colombia.