In 1821, after the Mexican War of Independence from Spain, the Mission San Fernando became part of Alta California, Mexico. In 1834, the Mexican government began redistributing the mission lands. In 1846, the Mexican land grant for Rancho Ex-Mission San Fernando was issued by Governor Pío Pico. It was bounded on the north by Rancho San Francisco and the Santa Susana Mountains, on the west by the Simi Hills, on the east by Rancho Tujunga, and on the south by the Montañas de Portesuelo (Santa Monica Mountains). The Rancho Ex-Mission San Fernando received a Federal land patent to retain ownership by the United States Public Land Commission in 1873 and was the single largest land grant in California.