They disappeared suddenly as a civilization...BUT....there are many out there who believe that they went somewhere else. No one really knows what happened to them Gene And....if you get into that stuff,there are some pretty bizarre theories as to what actually happened to them.
It was not just the Mayans who predicted this.Look up St. Malachi on Google.Here is a guy back in the 1100's who has accurately predicted the nationalities of every Pope up until the last one.Guess when the last one is? It is the one immediately following the one we have now...Pope Benedict.
The whole prophecy thing is weird. If people believe...that's fine.If they don't...that's fine too. Many believe that the things we are experiencing now,like global warming,frogs,bats and bees disappearing at an alarming rate are a result of a coming polar shift which will be cause all kinds of damage to the earth as Dec.23,2012 approaches, as there is going to be some weird planetary alignment happening that very night which hasn't happened for thousands of years.
Obviously we have some some shifts on this earth over time which has caused places like Antarctica to freeze over,as scientists have discovered that it once was a "normal" part of the world.Other places which are now deserts were once thriving with life.Who knows?
No matter what,it will be interesting to see how it all plays out.