By the time of the year zero came and went, the Maya had multiple cities that dominated the Mesoamerican region. Teotihuacán was the name of their dominant city. However, somewhere between 200 and 900 CE, they stopped using this area as the centre of government and commerce and expanded out into new areas. Civilization topped out in the millions.
Although things like agricultural troubles and natural disasters may explain some of the shifts in Maya civilization, a mystery still surrounds how the largest and most successful Mesoamerican group fell apart so quickly. Around the year 1000 CE, they migrated out of the cities, which were taken over by the Toltec tribe. Although eventual skirmishes between the Spaniards and native people did occur, it was not at all like a great city or kingdom battle depicted in the movies. When the Europeans arrived, they figured the cities where ruins of some other people and not associated with the Maya at all.