Recent discoveries of human footprints in Chile were dated circa 13,500 b.c. There were two basic theories of human dispersion from Berengia (Bering Sea walkover area when sea level was lower). One was the coastal route and the other via the interior after glaciers receded at the end of the Wisconsin opening the way past Watson Lake, toward the Peace and Frazier Rivers and points south. The coastal route would have allowed faster transit to South America (the Pacific coast).
There was a late settlement by Dorsett Eskimos with dogsleds that were the jet fighters of the day. It took them only 200 years along the Arctic shore to cross from Bering Strait to Greenland. They arrived about the same time at Greenland as the Vikings and Viking Settlements at East Bygd and West Bygd.
Some Eurasians travelling the interior route travelled down the Stikine River to settle the coast too. The Eurasians had more genetic similarity to Caucasians than Africans. They were mixed races that arrived in different waves.
Scientists have discovered the oldest human footprint ever seen in the Americas
There were other people that arrived from Western Europe, across the Pacific, and there is a possibility that some Mediterranean people arrived via boats that were caught in the Gulf Stream with the sailors being cast like lifeboat survivors on a sea voyage. Most of the small groups that made it to America were lost to history. What remains in history are the large, more numerous groups.
The Hai da of the Canadian coastal islands were boating people. Some believe they crossed the Pacific. Hai in Chinese language means ocean (like Shang hai). maybe they and others (Aleuts?) paddled along the Eastern littoral of Eurasia to Alaska and points south.
People like the Vikings arrived and made a lasting record of their presence. Farley Mowatt wrote a book named ‘The Farfarers; Before the Norse’ that describes a historical theory of Vikings following an earlier darker, shorter Mediterranean people to America plundering their camps on the way.
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It is possible that the Irish reached America before the Vikings by a couple hundred years. They may have crossed the continent and continued on to Hokkaido with their light skin boats facilitating trekking.
Interesting inferences may be made about some Viking or Irish influence on certain indigenous structural developments in the upper Midwest. Cahokia’s rise may have been precipitated by some exogenous leadership from European travelers, and a darker side; in North Dakota, has evidence of the first and possibly only stone defense wall around an indigenous village, in North America. There was evidence of a battle at the wall with skeletal remains from the conflict. Europeans and Middle Eastern people used defense walls for thousands of years.
Cahokia was the center of a true pre-Columbian civilization that reached to Mississippi the Carolinas and beyond.
Another pre-Columbian civilization was a tremendous construction in Amazonia that disappeared into the jungle just a few years after first contact. The biological isolation made the civilization vulnerable to disease from the first Spanish explorers.