why did the anasazi people leave their pueblo dwellings in chaco canyon?

Question

 based on brian fagans book on the anasazi people. 

Answer 1

In addition to the drought and marauding enemy theories, scientists suggest that things like poor sanitation, pests, and environmental degradation may have caused the Anasazi to move. If those other explanations require more of a stretch of imagination, there is yet another to ponder: the Anasazi communities may have gotten bigger than the culture could handle. The internal stress and strife, along with the external factors might have just made life too uncomfortable.

 

http://www.cliffdwellingsmuseum.com/history/the-anasazi/solving-the-mystery-of-anasazi-disappearance/