When did Native Americans first live in California?

Although some scholars think humans may have lived in what is now California as early as 48,000 years ago, people definitely lived there by about 8000 B.C.

From that time to the arrival of non-Native Americans in about A.D. 1550, the Indian population in California grew to about 300,000. The area had the highest concentration of Indians anywhere north of present-day Mexico.