Paleo-Indian sites dating from about 10,000 B.C. show that San Bernardino County has been inhabited for at least 12,000 years. In the past 300,000 years Native American tribes flourished in the area: the Gabrielenos in the West Valley; the Serranos in the foothills of the San Bernardino Mountains; the Vanyumes along the Mojave River; and the Mojave along the Colorado River.
On May 20, 1810, Franciscan missionary Francisco Dumatz led his exploring company into the valley. In honor of St. Bernardine of Siena’s feast day, Dumatz named the valley San Bernardino.
California was admitted to the United States in 1850. In 1853, San Bernardino was created from portions of Los Angeles, San Diego and Mariposa counties.
In the 1870s, prospectors in search of gold favored the Oasis of Mara as a camping spot. Legend says Twentynine Palms was named for the 29 palm trees that surrounded the oasis that offered a reprieve and water for venturing prospectors.
Twentynine Palms was incorporated into San Bernardino County in 1987.