Charred earth, shells, bones and human burials found in mounds on a plain in northern Bolivia are offering scientists new clues about the earliest known inhabitants of the southwestern Amazon.

The remains, excavated from raised areas known as “forest islands” on the Llanos de Moxos, an extensive savanna, show the area was inhabited between 10,600 and 4,000 years ago, according to new study published Wednesday in the journal Science Advances.

“In the late Holocene, about 2,500 years ago