Could people give me info about Mayan Long Count Calendar? And who have been the enemies of Mayans? Just spain

Spanish conquest of Mexico you know? Was that the only time? I mean i know in the film Apocalypto the Aztecs are the enemy of the Mayans but I wondered if there are any other ways I can portray people as their enemy in a film plot about the countdown calendar? I wondered if the Olmecs could be betrayed like the Aztecs were against Mayans in Apocalypto? I thought that every time a calendar writer writes in a bad date like 9/11/01, something bad happens to the mayans. Like the Olmecs take over their village. So I wondered if I could do that or was each date written every year or something? Or did they take years writing and writing and writing so many dates that it ended at 2012? I'd like to know more about the Long Count Calendar and how they wrote it? Thanks