The Anasazi were a civilization of Native Americans that thrived in the American Southwest from roughly 750 to 1150 CE. In their time, they became masters of pottery, architecture, and astronomy. As agriculturalists, many of the tribes developed intricate systems of irrigation that fed large fields of maize, squash, and beans. They built complex cities of stone and earth high above the ground inside cliff faces, or else sprawling desert-floor structures meticulously arranged in accordance with the heavens. A distinct culture emerged, one threaded with religion and tradition, and the population boomed.
But suddenly, sometime near the end of the 12th century, this advanced society began to collapse. With the civilization’s “golden age” still fresh in their memory, the people fled their ancestral homelands in one sweeping and mysterious exodus. In many instances they did not even bother bringing their possessions with them, simply leaving behindpottery and tools for future generations to come upon like signs of a once rapture. At other sites they went so far as to burn their homes and ceremonial structures as if to 
seal off and renounce their ancient traditions. For decades researchers have sought answers to explain this abrupt migration. A number of theories have since been formulated, each one of them viable yet consistently prone to the next scientific discovery or hypothesis. So which one of these theories is best? Which most adequately fills this unsolved gap in anthropological knowledge?
One of the earliest and most popular of explanations is the drought theory. Through the examination of tree rings, scientists observed signs of a long dry spell afflicting the southwest beginning late in the 13th century. This dry spell has come to be referred to as the “Great Drought,” and for decades it served as the most widely-accepted answer for why the Anasazi abandoned their homelands. The civilization simply had no choice but to, quite literally, move on to greener pastures.
But following a series of archaeological discoveries later in the 20th century, along with further examinations of tree rings showing evidence of additional devastating droughts existing throughout the centuries leading up to the Great Drought, the theory was brought into question. For why, if they had weathered many severe droughts before, did they choose not to endure this particular one? Moreover, signs indicated that the Anasazi had in fact already begun their evacuation before the full onset of this Great Drought.
New theories began to evolve, ones that did not discredit the Great Drought but provided it accomplices, claiming other forces had worked in combination with the drought to persuade the Anasazi to evacuate. For instance, through more tree ring research scientists discovered evidence of a “Little Ice Age” occurring around the time of abandonment. This dramatic cooling of the earth would explain why the Anasazi simply did not relocate to closer, higher elevations where it was moister instead of fleeing completely. Those higher elevations were too cold, yet to move even lower was to move into deserts even dryer. Thus the people were trapped and possibly forced to relocate somewhere drastically different, likely far to the south.
But this theory does not explain recent archaeological excavations, like those near Dolores, Colorado and Kayenta, Arizona in which Anasazi skeletons were revealed demonstrating extreme signs of violence. Could warfare have been a contributing factor in the Anasazi’s decision to leave the Four Corners region? Around the time of the Great Drought, new Indian tribes, like those of the Numic (Ute) and Athabaskan (Navajo, Apache) families were entering the region for the first time. Could it be then that the Anasazi, previously a peaceful people of hunter-gatherers, found themselves outnumbered and outfought in their struggle to claim the land’s dwindling natural resources? Strong evidence for warfare and outside harassment can be seen in the Anasazi’s move from their original homes in canyons and desert floors up into cliff-side fortresses. For instance, starting in 1150 CE the people began to leave Chaco Canyon, only to develop Mesa Verde in 1200 CE.
Still, the theory of warfare poses a whole new question. If competing tribes like the Navajo and Utes drove away the Anasazi from their homelands, why then didn’t they stay and enjoy the spoils? How could it be that the evacuation of sites like Chaco Canyon, and later Mesa Verde, was so sudden and complete – all the pottery and tools left behind? As mentioned, before departing certain sites some Anasazi groups destroyed their homes and ceremonial structures. These acts suggest a dramatic shift in the civilization’s spirituality. Could new religions, like those emerging from the Zuni and the Mesoamericans to the south, have drawn the Anasazi out of their homelands and into places sacredly anew? Could these once-masters of astronomy and agriculture have come to view the Great Drought as a sign of Mother Earth’s distaste for their manipulation of her, causing them to not only abandon their scientific and religious structures but destroy them?
On July 4, 1054, a supernova exploded across the sky. It was visible twenty-four hours a day and for twenty-three days straight. A few years later Halley’s comet soared past the earth. Both of these phenomena are thought to be depicted in Chaco Canyon. Could Chaco’s inhabitants have perceived the two incidents as omens – signs for them to leave before it was too late?
As it stands today, each of the above theories have their own individual merits and their own well-studied base of proponents. In all likelihood, the Anasazi abandoned their homelands because of a combination of these factors, if not all of them. On the other hand, perhaps that final missing link of evidence has yet to be discovered. Perhaps there is yet another explanation for why these people so abruptly and resolutely departed their magnificent stone cities, one that has nothing to do with drought, climate change, warfare, or spirituality. For like so many other ancient questions, perhaps the only constant answer is that we may never fully know.
