How did indigenous Mexicans get from the Siberian land bridge to Mexico without passing through California?
The great plains. The Gulf coast.
There is quite a lot of inhospitable country between the nice parts of CA and the nice parts of Mexico.
And CA seems never to have amounted to much as a site for civilization, nothing at all like these guys - https://en.wikipedia.org/wiki/Mississippian_culture
How did indigenous Mexicans get from the Siberian land bridge to Mexico without passing through California?
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They had Transporters or else they had some other form of magic. This is well documented by the various theories promulgated by science today.
Alternately, they took boats down the coast, skipping over the rich land and fishing resources, in a mad dash to become the first Mexicans.