Vibes is correct, the Mayans did not predict that the world would end in 2012, it is just the end of the last known "cycle" of their calendar. Their calendar was a remarkable achievement, extremely accurate. It had "cycles" that followed the movements of stars. At the end of a cycle, a new one would begin.
Only recently have FOR PROFIT "documentaries" begun interpreting the Mayan calendar as a prediction of doom.
Consider this, the Mayans couldn't even predict the demise of their own advanced culture. By the time Europeans arrived, they were living in only a shadow of their former "glory". The Mayans could read the stars, but they never invented the wheel. The Mayans built massive, wonderful structures, but never invented the cap stone...no archways, narrow corridors.
The Mayans had a five class structure, if you were on the bottom of it you could expect severe back problems in your teens and you could expect to be dead in your early thirties. They used up their soil, couldn't grow crops.
IMO, the Mayans are a remarkable people not because they predicted the end of anything, but because when the end came....they actually flourished and improved their daily lives. There ought to be a stone temple somewhere for the Mayan who first said, "We don't need no stone temple."