Although the Spanish Empire claimed California in the 1770s, much of the Central Valley, then a huge expanse of swamps and rivers, remained unexplored by the Spanish for several decades thereafter. The first Spaniards to encounter the Stanislaus River were Gabriel Moraga's 1806 expedition, who named the river "Rio de Nuestra Señora de Guadalupe", "River of Our Lady of Guadalupe". Fray Pedro Muñoz, traveling with Moraga, wrote of "immense quantities of wild grape-vines" along the Guadalupe River. In 1808, Moraga returned to the area to search for suitable mission sites, but was not successful. The river later became known as "Río de los Laquisimes", possibly derived from a Native American name for the river or surrounding area. Although the Spanish ultimately did not establish any missions in the Central Valley, they forcibly took thousands of Native Americans to missions along the coast, where they were converted to Catholicism and subjected to agricultural labor. Mission San José was the destination of many Miwok from the Laquisimes River area.