This is amazing, thanks for posting. For so much of history it feels like cultures were entirely isolated, and this presents some great evidence of remarkable early cross-polination.
I read this a while back (http://www.amazon.com/1177-B-C-Civilization-Collapsed-Turnin...), and one of the really interesting points was just how interconnected civilizations were, even way back in the Bronze Age. Long distance trade, diplomatic relations, war, stretching across hundreds and even thousands of miles.
Combine that with even more exotic luxury goods found in the tombs of Egyptian pharoahs (silk from china, spices from India and South-East Asia, or amber from the Baltic) and there had to have been a considerable amount of exchange.
A fit person can walk from the east to west coast of the U.S. in 60 days. Sure, poor conditions would slow people down, but overall I suspect people have always been fairly mobile.
I have to wonder how that would have worked out before modern times.
Ancient North America was not a wilderness; it was a crazy quilt of tribes and states and alliances, all bumping against each other.
Crossing from present-day New York to Vancouver in CE 700 you would have run into at least a dozen major ethnic groups, each of which would have needed to decide what to do with you.
It's astonishing the breadth of the face of the Earth early humans managed to traverse. If you want to understand the uniqueness of humans, it's not so much toolmaking, language or the thumb, it's our ability to migrate across and succeed in vastly different latitudes and our ability to change what this writer [1] calls a "cultural inventory"...all within the same species.
