Oak Park has had human occupation from about 5500 B.C. to the present day. It lies within a zone including the early Millingstone Horizon and inland Chumash Indians. Indians camped throughout the area as they collected acorns, yucca, and other food. The sites in the area include major villages, smaller camps and several rock shelters.
The location of Oak Park was originally part of Rancho Simi, a Spanish land concession in Alta California given in 1795 to Francisco Javier Pico, a soldier of the Santa Barbara company, and his two brothers, Patricio Pico and Miguel Pico by the Spanish government. Lindero Canyon Road follows the western border (lindero in Spanish) of the land grant.