From the website:
BC - AD Archeological research establishes prehistoric man in the Irvine area at least 12,000 years ago, possibly even 18,000 years ago. Scattered evidence of early campsites and rock shelters can be seen in the undeveloped parts of the City. Gabrielino Indians moved into the Irvine area 2,000 years ago, establishing dozens of villages. One village was located near the present