Simi Valley was once inhabited by the Chumash people, who also settled much of the region from the Salinas Valley to the Santa Monica Mountains, with their presence dating back 10,000–12,000 years.
Around 5,000 years ago these tribes began processing acorns, and harvesting local marshland plants.
Roughly 2,000 years later, as hunting and fishing techniques improved, the population increased significantly.
Shortly after this sharp increase a precious stone money system arose, increasing the viability of the region by offsetting fluctuations in available resources relating to climate changes.
The native people who inhabited Simi Valley spoke an interior dialect of the Chumash language, called Ventureño.

Simi Valley's name derived from the Chumash word Shimiyi, which refers to the stringy, thread-like clouds that typify the region.
The name could have derived from strands of mist from coastal fog that move into the Oxnard Plain and wind their way up the Calleguas Creek and the Arroyo Las Posas into Simi Valley.
The origin of the name was preserved because of the work of the anthropologist John P. Harrington, whose brother, Robert E. Harrington lived in Simi Valley.
Robert Harrington later explained the name: "The word Simiji in Indian meant the little white wind clouds so often seen when the wind blows up here and Indians living on the coast, would never venture up here when those wind clouds were in the sky.
The word Simiji was constructed by whites to the word Simi.
There are other explanations about the name Simi, but this one was given to me by my brother who worked over 40 years for the Smithsonian Institution and it seems most plausible to me".

Three Chumash settlements existed in Simi Valley during the Mission period in the late 18th and early 19th century: Shimiyi, Ta’apu (present-day Tapo Canyon), and Kimishax or Quimisac (Happy Camp Canyon west of Moorpark College).
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.
Other areas containing Chumash Native American pictographs in the Simi Hills are for instance by Lake Manor and Chatsworth.
Simi Valley was once inhabited by the Chumash people, who also settled much of the region from the Salinas Valley to the Santa Monica Mountains, with their presence dating back 10,000–12,000 years. Around 5,000 years ago these tribes began processing acorns, and harvesting local marshland plants. Roughly 2,000 years later, as hunting and fishing techniques improved, the population increased significantly. Shortly after this sharp increase a precious stone money system arose, increasing the viability of the region by offsetting fluctuations in available resources relating to climate changes. The native people who inhabited Simi Valley spoke an interior dialect of the Chumash language, called Ventureño.
Simi Valley's name derived from the Chumash word Shimiyi, which refers to the stringy, thread-like clouds that typify the region. The name could have derived from strands of mist from coastal fog that move into the Oxnard Plain and wind their way up the Calleguas Creek and the Arroyo Las Posas into Simi Valley. The origin of the name was preserved because of the work of the anthropologist John P. Harrington, whose brother, Robert E. Harrington lived in Simi Valley. Robert Harrington later explained the name: "The word Simiji in Indian meant the little white wind clouds so often seen when the wind blows up here and Indians living on the coast, would never venture up here when those wind clouds were in the sky. The word Simiji was constructed by whites to the word Simi. There are other explanations about the name Simi, but this one was given to me by my brother who worked over 40 years for the Smithsonian Institution and it seems most plausible to me".
Three Chumash settlements existed in Simi Valley during the Mission period in the late 18th and early 19th century: Shimiyi, Ta’apu (present-day Tapo Canyon), and Kimishax or Quimisac (Happy Camp Canyon west of Moorpark College). 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. Other areas containing Chumash Native American pictographs in the Simi Hills are for instance by Lake Manor and Chatsworth.
Simi Valley, California