[HamiltonJay]

Sure someone today could walk the americas, they know where they are going and what to expect.... however would a largely nomadic society just decide, hey, lets head south non stop? Not likely. The would expand as population and food and water demanded than simply head south young man...

I think 1000 years to spread out completely across americas is pretty darn fast given this sort of expansion and exploration pattern.

[RightWhale]

however would a largely nomadic society just decide, hey, lets head south non stop?

Of course. No question. Not the whole society. There are individual explorers in society. Even the animals have such. One lone person or polar bear takes off cross-country just to see what there is too see. Or maybe a single family unit.

Dad - We're going to the Amazon.

One day passes . . .

Kids - Are we there yet?