The Solutrian Migration at the end of the last ice age. I first saw articles and a documentary about this at least 8 years ago. Very credible, found evidence along the southern east coast as well as other places across North America. Alas, not politically correct regardless of the evidence, at least for now.
NOVA Nov. 9, 2004 America’s Stone Age Explorers
When they did a DNA test on the Ojibwa Tribe about 25% of it had chromosome X only found in Europe.