There are many theories of what could have caused the Mayan downfall . There are four main theory ’ s , such as Warfare , Disease , Famine , Disaster or Environmental Change ( DOEC ). Most people think that war caused the downfall of the Mayans . Heres why , too many records showed that they frequently fought their enemy . Another is that archeologists found many fortifications around many Mayan sites . Lastly , many paintings , monuments , and ceramics were found with warfare and the taking of slaves . That ’ s why many people thought the Mayans were warlike . Another theory is disease . The two main diseases people think caused the downfall are ; the yellow fever and the Peregrinus maidis . The maidis is caused by a bug . The sickness was mostly carried in the top Mayan crop , which is known as maize . Since it ’ s the top Mayan crop many people probably ate it not knowing and died . The next disease is the yellow fever , its mostly carried by the howler monkey . Which is native to the area . It can also be transmitted in bats and mosquitos . The yellow fever originated in Africa and wasn ’ t until the slave trade in 1500 ’ s that is came to the Americas . The next theory is famine , famine is the little or no food at all .