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A thousand years ago in what is now the American Southwest, the Anasazi (a Navajo word meaning "ancient ones" or possibly "ancient enemies") built dramatic adobe dwellings, or pueblos. Chaco Canyon was the center of Anasazi civilization, its many large pueblos probably serving as administrative and ceremonial centers for a widespread population.

How the Anasazi lived

Pueblo Bonito, one of the largest of the Chaco Canyon pueblos, is a good example of how the Anasazi lived. Pueblo Bonito rose four to five stories high — an astounding achievement for the time. Rooms surrounded a central plaza, and throughout the settlement were a number of kivas, meeting places that served a ceremonial purpose. The total population of Pueblo Bonito was probably around 1,200 people at its height. Surrounding the pueblo were a number of smaller dwellings and structures. Numerous communities looked to Chaco Canyon for political and religious guidance.

After the sixth century A.D., the Anasazi of Chaco Canyon and other settlements abandoned hunting and gathering in favor of cultivating crops such as maize (corn). To grow maize, they needed rain, but the area was dry and rain was sporadic. What rain did fall was hoarded and used sparingly and effectively. Evidence of dams, canals, and other water control features found by archaeologists shows the importance of water to the Anasazi.

Abandoning the pueblos

From the twelfth to the thirteenth centuries, many of the pueblos in Chaco Canyon were abandoned. What caused people to leave the pueblos, the centers of Anasazi society? One pueblo at Sand Canyon can provide clues. Archaeologists found evidence that when Sand Canyon was finally abandoned in the thirteenth century, the kivas were burned. Kivas were sacred ceremonial places; they would not have been systematically burned without cause. Many archaeologists believe the kivas were ceremonially burned, possibly as a way to "close" the kivas when people left. The Anasazi very likely did this because they never intended to return. Another important clue is that, at Sand Canyon, people left almost all their possessions rather than taking them. The Anasazi likely had a long and difficult journey ahead of them.

Why would the Anasazi leave — potentially for good — pueblos it had taken them decades to construct? Scientists have found one possible answer by looking at tree rings (a study called dendrochronology) in the Sand Canyon area. In the period between A.D. 1125 and 1180, very little rain fell in the region. After 1180, rainfall briefly returned to normal. From 1270 to 1274 there was another long drought, followed by another period of normal rainfall. In 1275, yet another drought began. This one lasted 14 years.

When this cycle of drought began, Anasazi civilization was at its height. Communities were densely populated. Even with good rains, the Anasazi were using their land to its limits. Without rain, it was impossible to grow enough food to support the population. Widespread famine occurred. People left the area in large numbers to join other pueblo peoples to the south and east, abandoning the Chaco Canyon pueblos and, later, the smaller communities that surrounded them. Anasazi civilization began a long period of migration and decline after these years of drought and famine. By the 1300s, it had all but died out in Chaco Canyon.

Was drought alone the only factor in the mass abandonment of the pueblos? Some archaeologists now believe that other factors — religious upheaval, internal political conflict, or even warfare — may have combined to exacerbate the effects of the drought. Whatever the root causes of the famine were, the archaeological evidence clearly shows it was devastating to the Anasazi.

How do archaeologists figure out when things happened? Find out more in "Dating the Evidence."