The Tataviam (Kitanemuk: people on the south slope) were a Native American group in Southern California. They traditionally occupied an area in northwest present-day Los Angeles County and southern Ventura County, primarily in the upper basin of the Santa Clara River, the Santa Susana Mountains, and the Sierra Pelona Mountains. They were distinct from the Kitanemuk and Gabrielino-Tongva.
The meager evidence concerning the language spoken by the Tataviam proved initially confusing to scholars. Eventually it became clear that there were two different sources for the extant word lists. The vocabularies recorded by C. Hart Merriam were from a Chumash dialect, probably the group referred to as "Alliklik", while the vocabularies recorded by Alfred Kroeber and John P. Harrington were Uto-Aztecan, probably the group referred to as "Tataviam." Further research has shown that the Uto-Aztecan language belonged to the Takic branch of that family, specifically the Serran branch along with Kitanemuk and Serrano. The last known Tataviam speaker died before 1916.
Estimates for the pre-contact populations of most native groups in California have varied substantially. (See Population of Native California.) Alfred L. Kroeber (1925:883) estimated the combined 1770 population of the Serrano, Kitanemuk, and Tataviam as 3,500, and their population in 1910 as about 150. A close study of genealogical records indicates that people of Tataviam descent survived into the twentieth century, although most had lost their traditional language. Tribal members continued to intermarry with other indigenous groups and with other ethnicities.
The Santa Clarita Valley is believed to be the center of Tataviam territory, north of the Los Angeles metropolitan area. They were noted as a distinct linguistic and cultural group in 1776, by Padre Francisco Garcés, and have been distinguished from the Kitanemuk and the Fernandeño.
The Spanish first encountered the Tataviam during their 1769-1770 expeditions. According to Chester King and Thomas C. Blackburn (1978:536), "By 1810, virtually all the Tataviam had been baptized at Mission San Fernando Rey de España." Like other indigenous groups, they suffered high rates of fatalities from new infectious diseases brought by the Spanish, as they had no immunity (medical). As of 2015, the Tataviam people are trying to continue and maintain a tribal government. Although the Tataviam used to be referred to as the Mission Indians of San Fernando, during the Spanish Missionaries, but as of the revolving time with the Mexican Government they have made many land grant treaties within the Tataviam territory. Following the commencement of California as a state, The United States Indian Affairs had decided to group the Tataviam with other Indian Villages in the same region, which is now Fort Tejon Indian Reservation.