MAYAS: They were among all the ancient american civilizations. They possessed the ability of astronomy , architecture, mathematics, painting and sculpture. They had no metal, water and no communication. Even though they had this problems they managed it. This was in the classic period from 250-900 CE. The Mayas low land culture suffered a decline that led to gradual cessation of building activities and the eventual abandonment of the ceremonial centers after 800 CE. According to a new theory that tries to explain this, the cessation of political and commercial contacts with Teotihuacan after about 550 CE led to the breakdown of centralized authority. This increased the authority of Mayan elites which brought the construction of more elaborate ceremonial centers. The increased population density brought the need for more intensive agricultural methods. Improved agricultural production made possible the late Classic flowering from 600-800 CE. But the last century of this era, food shortage and warfare led to a social and cultural decline. Those who survived were able to achieve a stable agricultural society but at a much lower level of population density and social organization.