Were the Native Americans believed to have migrated here from Asia over a land or ice bridge from Russia/Asia, or were they here before the last Ice Age and possibly already if the continents were all connected as Pangea or whatever?
Hi there, the Bering Strait migration theory is widely accepted, though there are disputes over timing. You can check out our FAQ on pre contact North America here:
https://www.reddit.com/r/AskHistorians/wiki/nativeamerican
With regards to the Pangaea question, no, the timing is wrong. Pangaea began to break up in the Mesozoic geological era, about 175 million years ago. Modern hominids, that is to say members of the genus Homo, emerged about 2.8 million years ago, while Homo sapiens only emerged about 200,000 years ago.
The Native Americans could not have come before the split of Pangaea because the family Hominidae, which would soon become the human species, didn't form until about 5 million years ago. At that point, the continents would look basically as they do today. There is no feasible way that Mesoamerican, Andean, etc. groups could not have formed without having a common ancestor in the Old World.
hi! this question would be better suited to /r/AskAnthropology, but there have been several threads here discussing this topic. Here are a few that may be interesting
Where did American (North) Aboriginals originate from? Did South American Aboriginals originate from the same place? - featuring /u/Reedstilt
Clovis culture and the first people in America - featuring /u/RioAbajo, /u/retarredroof, /u/archaeofieldtech, and /u/Reedstilt
In the settlement of Monte Verde, how did the people get there? - featuring /u/Reedstilt, /u/retarredroof, and /u/girlscout-cookies
Why weren't modern Siberians colonizing the new world prior to Europeans
These posts have all been archived by now, so if you have follow-up questions for any of the users, ask them here & tag their username to notify them