The third of those SBS docos was maybe the most intriguing. It dealt with the discovery of the oldest of the mesoamerican civilizations, the Olmec, traces of which might be dated as far back as 2000 bc. The amazing large stone sculptures, which could have taken up to ten years to make with primitive tools, are also something like a Stonehenge enigma in that the stones were transported up to 70 miles through heavy jungle and swamps to be brought to their cities. Some of the smaller art works and artifacts in wood, stone and jade are fascinating.
The fact that there have been a number of these early civilizations, roughly in the same time space (2-3000 BC through to 500 AD), but separated from each other by huge distances, with nothing in between but hunter gatherers or herders - Egypt/Mesopotamia & China & Mesoamerica - has to raise questions about contact and shared influences we know nothing about. For example, no such culture existed through North America & Siberia, meaning China and Mesoamerica had no contact by overland travel. Were there sea links?
