One thing that really blew my mind was learning that Beringian civilization lasted thousands years before the ice sheets receded enough for people to move into North America as Berginia was slowly swallowed by the sea. This is sometimes referred to as the "Beringian standstill population". By the time people made it down to Mexico they were likely another few distinct civilizations removed from Siberia.

https://en.wikipedia.org/wiki/Beringia#Human_habitation