Exactly there was no Indigenous peoples of North or South America, the Pre-Clovis were here, the Siberians came, the Vikings, the Japanese specifically from Island of Hokkaido as proved with DNA studies. The "new world" saw wave after wave of humans from all sides of the planet coming to explore and live, the first cultural/ genocidal war is now though to have been fought between Siberian land bridge people and the Clovis Europeans of the east coast. The DNA is pretty conclusive the east coast Indians are no where near the same genetically as the central and west coast Indians of the America's let alone the southern and meso American ones. Humans made it to Australia 40,000 years ago across open ocean by boat, same for the Polynesian Islands. Humans have had the technology to get to the Americas for at least 30000 years, and the evidence is mounting that people got here not 15000 years ago more like 25k or 30k BCE in pre ice age times.
It is always a pleasure to see someone who knows history, My Great Grandmother was a Doria from Genova of the same Doria's that funded Columbus needless to say we celebrate Columbus day as a family holiday.
The more I read, the supposed isolation of the (early) middle ages evaporates except in the heart of what later becomes Spain, France and Germany where if you were near no remaining Roman road, you were relegated to forest path limitations. Sowell makes a good point in showing the natural development characteristics of Europe versus Africa by citing a statistic that goes something like, “75% of Europe is within 50 miles of a navigable river or sea.”