The first European explorers arrived in 1769. Spanish missionaries under Father Junípero Serra founded Mission San Luis Rey de Francia on a former site of a Luiseño Indian village on the banks of the San Luis Rey River called Keish according to the Portolà expedition who visited in the 1769. In the early 19th century, the introduction of farming and grazing changed the landscape of what would become Oceanside. The area—like all of California—was under Spanish rule, then in 1821 under Mexican rule, and then the U.S. in 1848.