Most serious etymologists think it refers to streams, not the tribe. At the American Dialect Society, we’ve only found it back to 1892, and that was about the stream.
As far as the guy on that NOrth Georgia site/cite saying he 'thinks" it’s preserved in a letter to Andrew Jackson, … Show me the money!
Not exactly “recent,” but:
When I was a child, less than eight, we boys had a superstition that there was something called “cooties” which you could catch by touching or even getting near girls. Like most such, I mostly forgot about it later.
Later I learned of the existence of lice – head lice; and, later, of crab lice.
Much, much later, I learned that “cooties” is another word for lice. And under some circumstances, you really can catch them from girls. But it’s not something that should play any actual role in the life of an eight-year-old.