During the early 19th century, the Spanish military frequently raided the San Joaquin Valley, taking hostage hundreds of native Yokuts and Miwoks and forcing them to nearby missions – San Juan Bautista, San José, San Francisco de Asís, for example. Military violence and disease caused the extermination of much of the remaining valley population, including those in a series of 24 villages along the lower San Joaquin River described by Moraga. Those natives that lived in the foothills and the higher mountains of the Sierra remained undisturbed for the most part, and fought back against the Spanish while sheltering their valley counterparts.