Costanoan Shell Mounds date back to 3,500 BC

Burial mounds with artifacts and middens dating back to an estimated 3,500 BC exist in the greater Bay Area. The people of these mounds may have been the ancestors of the Costanoans, as the Spanish named the coast people.

The Costanoan linguistic group, comprised of eight separate languages spoken by 50 autonomous tribes (each with its own dialect), has been traced to 500 A.D.

Image: Bancroft Library (brk00001577_24a) by
Louis Choris, 1816
From FoundSF