The people in Coastal California were Native Americans. In the past, the area that was called "California" was not just today's California. This area covered the Mexican lands south of it, as well as Nevada, Utah, and parts of Arizona and Wyoming. The Spanish called the part of the land that later became part of the United States "Alta California" (Upper California) when it was split from what became "Baja California" (Lower California). In these early times, the borders of the Sea of Cortez and the Pacific coast were not well known, so the old maps wrongly showed California to be an island. The name comes from "Las sergas de Espladián" (Adventures of Spladian), a 16th-century book by Garci Rodríguez de Montalvo, where there is an island paradise called California.