The end of the classical Maya period [The Terminal Classic] is a mystery that has been puzzled over for decades. Why did the Mayans suddenly abandon and let the jungle grow over the walls and temples?
In the 900s (AD) there was a short and a very severe drought. The erection of defensive walls indicates that the drought was followed by an increase of warfare, even to the point that people dismantled temples and used their stones for the walls. The drought and wars are the most probably explanations for the end of the classical Mayan cities. However, Mayan territories had suffered from many droughts, even one that was recorded by Mayan scholars to last from 300 BC to 200 BC, so we don’t know exactly how and why the abandonment happened.
The Mayans stayed in the area, however, and lived in cities until the coming of the Conquistadores. Today, about 5 million still live in El Salvador, Belize, Honduras, Guatemala and southern Mexico.