What explanations do historians offer for the disappearance of mayan city states?

The disappearance of Mayan state remains the greatest mysteries even to historians or Mesoamerica history. There are many theories that even explain what happened, one of those example is that there was an uncontrolled warfare of Mayan and city states. And also there was a theory that the Mayan migrated away from the old Mayan hearland and go back to their village life. The jungle reclaimed the great plazas and pyramids. Stone by stone.