Atlantis, Mayan Calender, and the 4th, 5th ,6th worlds

If there is one thing that has always caught my attention is that of the afterlife, and past that we have left behind. One thing that I recently started to wonder was about different civilizations through out the world. It is amazing to think that Carthage had working plumbing as early as 500 BC, and maybe even earlier. I thought about other civilizations that dated back even further than 500 BC, and were still pretty educated. There was the other Greek colonies, Babylon, and of course Egypt. What came before Egypt though, I am sure there is some evidence as to other civilizations in the Middle East and Asia. Still there has to be some others that were there way before Egypt and were completely civilized. I mean there is no way we were hunters and gathers and then only a few centuries later we are building pyramids. It is possible that there were civilizations far more advance than we are now that have existed, but were possibly wiped out by a "nuclear war" of some sort. The pyramids were built around 3200 BC, around this time Atlantis is supposedly to have sunk. This in turn ended the 4th world. The 5th world then began. There are theories according to the Mayan calender that we are working on our 6th World which will begin in December of 2011-2012. Not exactly sure what this means, but it would make sense. This would mean that there were other civilizations that did exist before Egypt that were complex, but lost some how to history.