independent developments.
The indigenous people of the Americas did indeed travel all over the 2 American continents and maintained extensive, far reaching networks. That is how corn (maize) spread from its place of original domestication in Mesoamerica to people all over North and South America.
The independent development of the concept of zero in Mayan society is an example of how advanced some people were in various parts of the world. It's the people who discount the intelligence and capabilities of Indigenous Americans who insist that they could not have developed their civilization and mathematical skill in calculating the timing of a year, which was more accurate than any place else on the world. Those people claim that the Mayans must have got their knowledge from some vague, nebulous, imagined contact with civilizations elsewhere in the world.
The same thing happened regarding the city that we now call Cahokia. It was a huge Native American city in the North American Midwest. The people had built great earthenwork mounds and temples. But the city was abandoned before Europeans arrived. As American farmers moved westward and encountered those mounds and remnants of the once great city, they decided that no "Indian savages" could have achieved such developments, so they invented out of pure imagination, with no facts, stories about who the former inhabitants of the city had been. Some said that they were descendants of the "lost tribes of Israel (a doctrine in Mormonism). Some said that they were the descendants of Atlantis survivors. Regardless of whom they believed that the city's builders and inhabitants were, they agreed that the "wild, savage Indians" had destroyed that city. Therefore, the Americans settling the area from the east were justified in taking the land from its inhabitants.
= new reply since forum marked as read