Strathearn, served as the headquarters of the rancho.
José de la Guerra y Noriega, a Captain of the Santa Barbara Presidio, who had begun to acquire large amounts of land in California to raise cattle, purchased Rancho Simi from the Pico family in 1842.
There are many Chumash cave paintings in the area containing pictographs, including the Burro Flats Painted Cave in the Burro Flats area of the Simi Hills, located between the Simi Valley, and West Hills and Bell Canyon.
The cave is located on private land owned by Boeing, formerly operated by Rocketdyne for testing rocket engines and nuclear research.
The city sits next to Thousand Oaks, Moorpark, and Los Angeles.
The city's 2014 population has been estimated at 126,871, up from 111,351 in 2000.
The origin of the name was preserved because of the work of the anthropologist John P. The word Simiji was constructed by whites to the word Simi.The city of Simi Valley is surrounded by the Santa Susana Mountain range and the Simi Hills, west of the San Fernando Valley, and northeast of the Conejo Valley.It is largely a commuter bedroom community, feeding the cities in the Los Angeles area and the San Fernando Valley to the east, and cities in Ventura County to the west.It was one of the largest lands, but later when Mexico became independent from Spain, land was handed out much more freely.The Simi Adobe-Strathearn House, later the home of Robert P.