The Luiseño are the most Southwestern group of Shoshonean people in the greater North American desert. The name Luiseño came from their having lived in close proximity to the Spanish mission San Luis Rey (1798-1834) which is located in northern San Diego County near Oceanside, California. Originally, the Luiseño may have been called Payomkawichum ('The Westerners') by neighboring people and Ataxum ('The People') by themselves.
The Luiseño occupied parts of north coastal San Diego County and Riverside County in pre-Hispanic (before 1769) Southern California. It is theorized that the Luiseño came into Southern California approximately 5,000-7,000 years ago during severe altithermals (drought periods) from the Basin areas east of the Sierra Nevada Mountains. Their Shoshonean neighbors like the Cupeño, Cahuilla, Serrano, Gabrieliño and Chemehuevi were part of this migration. The Southern California environment is dominated by scrub plant communities that include the following :