Where does the name California come from?
When 16th century Spanish explorers named their new discovery "California" they thought they had just found a giant island off the western coast of Mexico.
These first Spanish explorers had actually discovered the peninsula we know today as Baja California.
"California," the name of the discovered "island," first appeared in 1539. It was based on a fictitious island in a popular Spanish book called "Las Sergas de Esplandian," ("The Exploits of Esplandian") by Garci Ordonez de Montalvo. The island was described in the book as a fabulous island of gold and griffins that was inhabited by Amazons.
—The Fact Monster