Brent Kennedy's book The Melungeons: Resurrection of a Proud People makes a convincing arguement for Turkish settlers in the Appalachian highlands of the United States. When the Scotch-Irish traveling down the Big Valley got to eastern Tennessee, they encountered a Mediterranean folk who'd got there first. They called themselves "melangeons," a Portaguese term meaning "shipmates" which is apparently cognate with the Turkish expression "melun can" (accursed soul). Perhaps, descendents of the 400 or so galley slaves (shipmates who were accursed souls!) who Sir Francis Drake liberated in South America, and apparently put ashore in North Carolina.
And, let's not forget the incredibly detailed maps of our coasts made by pirate and cartographer, the Turk Piri Ris.
Mr. Kennedy may be trying to hard to make his case, but his book is fascinating reading. Cognates of Turkish terms turn up in Indian place names -- kan tok -- full of blood, for example. (think about it)
The melungeons don't look Turkish. They look Portugese.
Adair thought that the Indians came from the Lost Tribes of Israel, and saw resemblences between Hebrew and the native tongues. Who knows.