Maybe they had African slaves too.
That would probably not be the case. However, the location of Avalon is still not been verified. Tales of land to the west go back pretty far.
Early settlers around Louisville found quite a bit of evidence they considered Welsh, especially that it was used as a kind of diplomatic and "educated" lingua-franca by the various Indian tribes, much like the Europeans then used Latin.
Several stone forts atop mountains in Georgia, Alabama, and Tennessee that obviously were desperate attempts at defence by some outnumbered European people, plus Cherokee and other legends suggesting that they had to overcome a scattered white (blue) eyed people en route from the Gulf Coast area to their home in the southern Mountains, migration circa 650-720 AD...
Celtic inscriptions dated to the 480-720 AD era are atop several mountains in West Virginia.