What Happened to the Ancient Maya?

The famine theory

They practiced basic subsistence agriculture.

As the Maya civilization advanced, the cities grew, their population growing much larger than could be fed by local production.

A famine or other agricultural calamity affecting these basic crops could certainly have caused the downfall of the ancient Maya.

Civil Strife theory

The idea that a hungry, overworked working class might overthrow the ruling elite is not too farfetched, especially if warfare between city-states was as endemic as researchers believe.