Tomas was a son of José Antonio Yorba, the grantee of Rancho Santiago de Santa Ana in present-day Orange County.
Nine days later Vicenta Sepulveda, then a widow and going by her maiden name, also applied for some of the same La Sierra lands.
With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored.
Through several acquisitions Willitts J. Hole (1858–1936), a Los Angeles businessman, purchased much of the original Rancho, eventually owning more than 17,000 acres (69 km2).
In 1942, the U.S. Army purchased 1,239 acres (5 km2) of the ranch from the Hole estate, and set up Camp Anza, a World War II disembarkation facility.
[12] Western Riverside continues to be referred to as La Sierra, with four separate city neighborhoods beginning with the name.