The numerous theories that have been proposed to explain the abandonment of the San Juan and other areas by the Anasazi at the end of Pueblo III times are discussed.
The theory of the Great Drought of A.D. 1276-1299 is rejected as a total cause because the Chaco Canyon center was abandoned long before this “drought.” Drought in general is questioned because climatic data indicate that in some cases inhabitants of more favored areas migrated to less favored areas.
The theory of disastrous arroyo-cutting suffers from insufficient evidence. In addition, it does not seem to have taken place at Canyon de Chelly, and it would not have been able to affect the mesa-top farms at Mesa Verde.
The theory of Athapaskan raiders is favored by the defensive trend of Pueblo architecture. Although probably weaker militarily, the nomads could have caused abandonments by use of guerrilla tactics. Despite a lack of positive archaeological evidence, the possibility of a sufficiently early arrival of the Athapaskans is suggested by legend, glottochronology, and indirect archaeological evidence in the Largo-Gallina area.
Inter- and intra-village feuds would not cause large areas to be deserted, especially if land shortages were the cause of conflict, and the hypothesis of devastating disease fails to account for the population increases of Pueblo IV times and is not supported by historical data.
It is concluded that multiple causes will have to be cited to explain all the Pueblo abandonments but that nomadic raiders appear to be the best general explanation, given the available data.