San Bernardino County, California: History
=== Indigenous ===
The indigenous peoples that lived in what is now San Bernardino County were primarily the Taaqtam (Serrano) and ʔívil̃uqaletem (Cahuilla) peoples who lived in the San Bernardino Valley and the San Bernardino Mountains; the Chemehuevi and the Kawaiisu peoples who lived in the Mojave Desert region; and the 'Aha Makhav (Mohave) and the Piipaash (Maricopa) peoples who lived along the Colorado River. These groups established various villages and settlements throughout the region that were interconnected by extensive trails.
Wa'aachnga was a major Tongva village site, also occupied by the Serrano and Cahuilla, located near what is now the city of San Bernardino. The village was part of a trade network along the Mohave Trail that connected villages in San Bernardino County from the Colorado River to the Los Angeles Basin. Wá'peat was a Desert Serrano village located near what is now the city of Hesperia. It was part of a series of villages located along the Mojave River. By the late 1700s, villages in the area were being increasingly encroached upon by Spanish soldiers and missionaries, who were coming into the region from Mission San Gabriel.
Spanish Missionaries from Mission San Gabriel Arcángel established a church at the village of Wa'aachnga, which would be renamed Politania in 1810. Father Francisco Dumetz named the church San Bernardino on May 20, 1810, after the feast day of St. Bernardino of Siena. The Franciscans also gave the name San Bernardino to the snowcapped peak in Southern California, in honor of the saint and it is from him that the county derives its name. In 1819, they established the San Bernardino de Sena Estancia, a mission farm in what is now Redlands.
Following Mexican independence from Spain in 1821, Mexican citizens were granted land grants to establish ranchos in the area of the county. Rancho Jurupa in 1838, Rancho Cucamonga and El Rincon in 1839, Rancho Santa Ana del Chino in 1841, Rancho San Bernardino in 1842 and Rancho Muscupiabe in 1844.
Agua Mansa was the first town in what became San Bernardino County, settled by immigrants from New Mexico on land donated from the Rancho Jurupa in 1841.
Following the purchase of Rancho San Bernardino and the establishment of Fort San Bernardino (then later the town of San Bernardino) in 1851 by Mormon colonists, San Bernardino County was formed in 1853 from parts of Los Angeles County by an act of the California State Legislature. Some of the southern parts of the county's territory were given by an act of the legislature to Riverside County in 1893.