That's not quite what Wikipedia says on the subject. They do agree on the southern part, just not the LA part.
I was referring to the origin of the current/recent elevation into national culture. Didn't know it was that old of a concept. Celebrities discovered "Roscoe's" in LA, especially popular with hip hop community, and it became a thing.
Well that's pretty much true of any "hyped" thing. Either way, thanks for piquing my interest in the matter. Learn something new everyday!