Rancho Los Nietos was one of the first, and the largest, Spanish land concession in Alta California. Located in present-day Los Angeles County and Orange County, California. Rancho Los Nietos was awarded to Manuel Nieto in 1784. After an appeal by the San Gabriel Mission padres, Rancho Los Nietos was later reduced and Rancho Paso de Bartolo was once again a possession of the mission. The rest of the rancho remained intact until 1834, when Governor Jose Figueroa officially declared the Rancho Los Nietos grant under Mexican rule and ordered its partition into six smaller ranchos.

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.