 European explorers flying the flags of Spain and of England explored the Pacific Coast of California beginning in the mid-16th century.Francisco de Ulloa explored the west coast of present-day Mexico including the Gulf of California, proving that Baja California was a peninsula, but in spite of his discoveries the myth persisted in European circles that California was an island.Rumors of fabulously wealthy cities located somewhere along the California coast, as well as a possible Northwest Passage that would provide a much shorter route to the Indies, provided an incentive to explore further.