The Russians established their outpost of Fort Ross in 1812 near Bodega Bay in Northern California, north of San Francisco Bay. The Fort Ross colony included a sealing station on the Farallon Islands off San Francisco. By 1818 Fort Ross had a population of 128, consisting of 26 Russians and of 102 Native Americans. Spanish concern about Russian colonial intrusion prompted the authorities in New Spain to initiate the upper Las Californias Province settlement, with presidios (forts), pueblos (towns), and the California missions. After declaring their independence in 1821 the Mexicans also asserted themselves in opposition to the Russians: the Mission San Francisco de Solano (Sonoma Mission-1823) specifically responded to the presence of the Russians at Fort Ross; and Mexico established the El Presidio Real de Sonoma or Sonoma Barracks in 1836, with General Mariano Guadalupe Vallejo as the 'Commandant of the Northern Frontier' of the Alta California Province. The fort was the northernmost Mexican outpost to halt any further Russian settlement southward. The Russians maintained it until 1841, when they left the region.