I know that this poses another question - rather than answering the original one (sorry!)but has anyone come across the theory that the Mandan Indians of the Upper Missouri were descended from the Welsh?
I think it was George Catlin who first made this hypothesis. He noticed that the Mandans were often pale-skinned, had many words in their language which were similar to Welsh words and used 'bull-boats' which were very like Welsh coracles. I have a hazy memory of reading somewhere that this has been attributed to a Welsh prince, called Madoc, who was supposed to have crossed the Atlantic before Columbus (although how he got as far as North Dakota and then decided to settle there is beyond me!). Does anyone have any updates on this hypothesis?