You may have already posted on this particular story. If so, please forgive me for duplicating.
Interesting. With newer technology, we’ll be able to find out a lot more about all of these ancient civilizations in different parts of the world.
The Mayans had obviously had big metropolitan areas, and then something happened - possibly attacks from the Aztecs, but possibly also some disease that reduced their population even prior to the European arrival (which brought European diseases).
Of course, our big disease in the West (Europe and the Americas) is abortion, which has reduced our native populations by close some 100 million.