"Essential California: Who claims a name? - Spanish conquistadors with a taste for then-contemporary fiction probably first used the name for the peninsula around 1535, a few decades after the book was published. The whole region was then referred to as California for a long while, before the northern part became Alta California and the southern peninsula Baja California. .."
https://www.latimes.com/california/story/2020-02-12/baja-name-california-newsletter 
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