Unlike the E. Hemisphere, the cultures of the Americas seem to almost exist in perfect isolation.
The nations of N. America knew nothing of the Maya. People in the Caribbean knew next to nothing of S. America. Inca didn't really know the Aztecs. Inuit didn't trade with the Nez Perce.
Now contrast that with the other side of the world.
Romans knew vaguely about the Chinese. The Chinese traded with east Africa. India knew of almost everyone. Egypt traded with many far-flung ports. Hundreds of ethnic groups were aware of the others.
So what was the case with the Western Hemisphere? Were they just thousands of years behind the East? Was this hemisphere just to thinly populated? Could it have been the strong nomadic nature of most of the population that prevented sophisticated states to develop that could have lead to more established trade networks?
hi! while you're waiting for direct responses to arrive, you may be interested in checking out this section of the FAQ: it contains information on trade networks and so on in the Americas
Well I believe its a misconception that native tribes had no knowledge of each other over great distances. There were vast trade networks across the continent evidenced by items traded to natives on the east coast being found in the possession of west coast tribes. You also have to remember that at the time that most European accounts of natives were written the north american people were experiencing the tail end of practically apocalyptic epidemics. Trade, communication and really knowledge in general is severely disrupted when 50% of the population suddenly dies from smallpox. Because of this you have accounts like this. ''North America was inhabited only by wandering tribes who had no thought of profiting by the natural riches of the soil,'' Alexis de Tocqueville, 1835.
http://www.academia.edu/4998969/Trade_Routes_in_the_Americas_Before_Columbus
Edit (something I just thought of) It has been theorized (I personally agree with this) that east/west migration and trade is much easier than north/south due to environmental factors. As you migrate east/west you stay predominantly in roughly the same climate making it more likely your crops will be viable, animals will adapt easily etc. Because Eurasia is oriented along the equatorial axis trade and migration is easier in an east/west direction. North and South america are oriented perpendicular to that which may explain more limited trade and cultural integration between north/south america.