End of an Era
In any event, the big cultural centers broke down.
Over time, Mesa Verdeans had abandoned their mesa-top structures to build elaborate, multi-room cliff dwellings in the same area. At Chaco, pueblos on open ground were given up for new ones at the base of cliffs. All of that suggests that they sought protection from an enemy.
The newer villages and towns must have been more defensible. Yet, if an enemy raided the agricultural fields and destroyed the remaining crops, the Anasazi might have fled to safety only to face starvation.
Then there were the droughts. Tree-ring dating tells us that there was a 50-year drought commencing in A.D. 1130 and another from about A.D. 1275 to 1300. By A.D. 1300 Chaco, Mesa Verde and Kayenta were abandoned and their former residents scattered to the East and South, gone but not forgotten.