Once a valley of the coastal Miwok, Pomo and Wintun peoples, called the "Valley of the Moon" in their legends, the valley was selected by the Franciscan order of Spain as the site to build the Mission San Francisco Solano, the northernmost mission in their chain of twenty-one missions built in Alta California. Established in 1823 and named to honor St. Francis Solanus, Mission Solano was the sole California mission established under the rule of a newly independent Mexico. Within two generations of the Spaniards' arrival, however, the indigenous societies of the region were dispossessed of their land and decimated by diseases to which Europeans were resistant. Soon after the Sonoma mission was built, it was secularized by the Mexican government, and, under the orders of Lieutenant, later General Mariano Guadalupe Vallejo, el Pueblo de Sonoma (the town of Sonoma) was laid out in the standard form of a Mexican town, centered around the historic plaza, which is still the town's focal point.