Decline of Anasazi
There are a few major theories floating around, most of which are presented here. The first thing to recognize, though, is that the ancient Pueblos did not completely disappear: the present-day Pueblos are direct descendants of those indigenous Americans that seemed to have disappeared in the year 1300.
The 50 Year Drought
The most popular theory of the past number of years, it is possible that the ancient Pueblo simply took one too many hits from droughts.
The Anasazi lived in the region of Southwest America and the reason for their decline is a mixture of environmental and societal pressures which is not clearly known. It is believed that their decline could also be as a result of drought, climate change, cannibalism or religious shifts. All these reasons show there are a lot of discrepancies concerning their decline