700 years ago, in the area that we today know as Arizona and New Mexico, the Anasazi people came en masse from the north to build large stone settlements. Their predecessors (the Hohokam) had built with sticks and mud, and as a result the older settlements are much harder to find today. The Anasazi settlements stand as grand, abandoned cities that now house a mystery: why did these people move south? What would cause a thriving civilization to pull up stakes and abandon its homeland?
A New York Times article surveys the current archaeological thinking:
Scientists once thought the answer lay in impersonal factors like the onset of a great drought or a little ice age. But as evidence accumulates, those explanations have come to seem too pat -- and slavishly deterministic. Like people today, the Anasazi (or Ancient Puebloans, as they are increasingly called) were presumably complex beings with the ability to make decisions, good and bad, about how to react to a changing environment. They were not pawns but players in the game. Looking beyond climate change, some archaeologists are studying the effects of warfare and the increasing complexity of Anasazi society. They are looking deeper into ancient artifacts and finding hints of an ideological struggle, clues to what was going through the Anasazi mind.
What makes the puzzle weirder is that the Anasazi never went back to their northern homeland. Even if climate change (for example, a drought in the thirteenth century) caused the initial migration, why didn't the Anasazi people return to their northern cities after the rains returned, just a few decades later?
In the remains of Sand Canyon Pueblo, in the Mesa Verde region, Kristin A. Kuckelman of the Crow Canyon Archaeological Center in Cortez, Colo., sees the story of a tragic rise and fall. As crops withered, the inhabitants reverted from farming maize and domesticating turkeys to hunting and gathering. Defensive fortifications were erected to resist raiders. The effort was futile. Villagers were scalped, dismembered, perhaps even eaten. Families were slain inside their dwellings, and the pueblo was burned and abandoned. Curiously, as was true throughout the region, the victors didn't stay to occupy the conquered lands.