One theory suggested by Dr. Michel Peissel, is that the decline was caused by the pressure of war and invasions. It’s possible that the Mayans may have been in frequent warfare with surrounding civilizations and/or tribes. This frequent warfare could have caused the Mayans to flee and discard their conventional agricultural methods. With raging war and lack of food, the Mayans may have fled for survival. War with strange new people could have caused disease to break out and mayhem to occur as panicked Mayans fought for survival. This leads us toward the next theory.
A government controls its society, influences its society and sometimes deceives its society. A corrupt government can poison the minds or its subjects and bend them to its will using misleading laws and promises of justice. A corrupt government can infect the minds of the honest and humble, but when a government goes too far it can lead to revolt. Broken promises, high taxes, unjust acts and more can cause peasants to rebel against authority. Every government in the world has corrupt officials who lie to their people, officials who neglect their responsibilities to their people and officials who even break their own laws to pursue their own objectives. Even today in America you can see these officials in power as you read this page. Therefore it is possible that the decline may have been caused by faulty officials. The breach in the ecological balance prompted deep agricultural crises that eventually led to famine. This situation pushed residents up to the north. Under these terrible conditions, heated political melees came in no time and “the people lost faith in their rulers.” (Sylvanus G. Morley).
Another theory by Mayanists, Thomas Gann and J.E.S. Thompson, that is seemingly holding water, is
References: Morley, S. G. (1983). The Ancient Maya. Stanford: Stanford University Press. Thompson, J. E. (1927). The Civilization of the Mayas. Field Museum of Natural History.