Rancho Santiago de Santa Ana was a 63,414-acre (256.63 km2) Spanish land concession in present-day Orange County, California, given by Spanish Alta California Governor José Joaquín de Arrillaga in 1810 to Jose Antonio Yorba and his nephew Pablo Peralta. The grant extended eastward from the Santa Ana River to the Santa Ana Mountains, with a length of more than 22 miles (35 km).

Orange County is a county located in the Los Angeles metropolitan area in Southern California, United States. As of the 2020 census, the population was 3,186,989, making it the third-most-populous county in California, the sixth-most-populous in the United States, and more populous than 19 American states and Washington, D.C. Although largely suburban, it is the second-most-densely-populated county in the state behind San Francisco County. The county's three most-populous cities are Anaheim, Santa Ana, and Irvine, each of which has a population exceeding 300,000. Santa Ana is also the county seat. Six cities in Orange County are on the Pacific coast: Seal Beach, Huntington Beach, Newport Beach, Laguna Beach, Dana Point, and San Clemente.