>> No, the Athabascans invaded North America from Asia.
>
>Really? WOW, talk about migrations. I'm surprised there wasn't more
>cultural diffusion along the way. I'd at least expect them to come down
>via Iceland, which would be right in line with the main Atlantic
>currents.
The thought is that both groups migrated from a common origin in Central
Asia, which seems to generate invading cultures, (Athabascans, Aryans, Turks,
others of varying success). The Athabascans were unusual in that they were
able to get to North America as well. It's thought that there was cultural
diffusion along the way - but the remains have been exterminated by susequent
invasions along more-or-less the same routes.
The Iceland route requires serious deep sea vessels, which (probably) weren't
available. Also, the Athabascans are in northwestern North America, although
they made it as far south as the Mexican border; the Navajo are Athabascan.
>Is there evidence that they crossed Asia to reach western
>europe? Is this archeologically prior to the aryan migration?
No evidence I'm aware of, other than easier travel via the land route and the
remaining language isolates in Siberia. Yes, it's thousands of years prior
to the Aryan migration - something like 6000 or 8000 BC.