[RightWhale]

There is some doubt that Arthur took his army to Gaul at all. He might have gone east from Wales to fight the Saxons without leaving England, He might have got only as far as Birmingham. There are a lot of stories in antiquity about a golden land to the wast, Arcadia, a rustic paradise. It's possible they were based on some knowledge of America 500 AD or 1500 BC. Ship travel between old and new world would have been undependable, and they didn't have radio, probably, so word of the new world would have been spotty. There is no question that many people came to America and have been doing so for a long time. Maybe some person named Madoc who was also well-known before he left the old world mounted a fair-sized expedition. Or maybe Avalon was Ireland.