The Lomaki Pueblo ruin [left], located in the Wupatki National Monument near Flagstaff, Ariz., was a small Anasazi village that housed one to three families, similar to the small villages in nearby Long House Valley. [image credit: Mara Gregory]

During the mid-1980‘s, Jonathan Haas, an archaeologist and curator at Chicago's Field Museum, spent a lot of time digging around in Long House Valley, a dry, scrubby bit of land in a desolate corner of Arizona. He was piecing together the history of a mysterious group of people known as the Kayenta Anasazi who lived there around 900 years ago. As Haas and a team of archaeologists mapped and excavated areas of the valley, the story of the Kayenta Anasazi that emerged was one of environmental catastrophe, remarkable cooperation, widespread warfare, and ultimately cultural collapse as the residents of Long House Valley completely abandoned the area by AD 1300.

Haas focused his work on mapping changes in the pattern of Kayenta Anasazi settlements in the valley. These changes gave him important clues about how the lives of the valley’s residents had changed over time. He found that an assortment of tiny villages, each housing several families, were evenly distributed across the valley’s floor by around AD 1100. People living in neighboring villages surely interacted with one another, but each village was independent. There is no sign of warfare at this time, either between villages or between Long House Valley residents and outsiders. This was a fairly prosperous time for the inhabitants of the valley: by analyzing tree rings and soil samples, archaeologists have found that rainfall was relatively plentiful, making for fertile fields and abundant harvests of corn, squash, and beans.

But beginning around AD 1150 all of this abruptly changed. Drought set in. Fields were ravaged by erosion, and farming became more and more difficult. Even pools and rivers that provided drinking water began to dry up. Over the next century, the people living in the southern half of the valley abandoned their land and crowded into the northern part of the valley. By AD 1260 a new kind of village had replaced the tiny, unorganized villages that had dotted the valley in centuries past. In these new villages a large, central settlement was surrounded by several smaller dwellings. The entire population of the valley gathered into five of these village clusters.

What led the people of Long House Valley to leave their homes and congregate in larger, more concentrated settlements? Haas has concluded that it was a way for them to survive in a rapidly changing environment. In the face of a generation-long drought and steadily declining food and water sources, the Kayenta Anasazi in the Long House area banded together. They moved into tight clusters and began working together to survive. They built common rooms in the central settlement of each village for grinding shared stores of corn into flour. They also constructed reservoirs at each village to maximize their shared access to the dwindling water supply. These changes are a testament to remarkable cooperation among the Long House residents during a difficult time.

The Wupatki Pueblo [right] is a large multi-room structure that may have housed as many as 100 people. It served as the center of the surrounding community, much like the larger villages in nearby Long House Valley. [image credit: Mara Gregory]

But there was also a darker side to these changes - the position and layout of the village clusters hint at frequent warfare. One of the villages, called Organ Rock Ruin today, is set atop a sheer, 200-meter cliff at the edge of the valley. The only way to access the village, today and in the past, is to scramble up a steep slope and climb the last 15 meters up a vertical cliff face using carved handholds. The nearest sources of food and water were located far below the village, on the valley floor. You can imagine that hauling food and water up the cliff day in and day out must have been beyond inconvenient. So why did the residents of Organ Rock Ruin go through so much trouble to build their village in such an inaccessible place? Haas thinks that they were protecting themselves from frequent raids by enemy groups.

Other villages in the valley were also built in defensible locations. Some were even partially surrounded by walls. Villages were also positioned on high ground so that each village had a view of other villages. In one case, a large V-shaped notch was dug into a hill to create a direct line of sight between two villages. A view of other villages may have been important for signaling and quick visual communication. Some villages also commanded a view of geographical entryways into the valley, presumably so that approaching enemy raiding parties could be spotted early. Haas assumes that the villages weren’t built in inconvenient places by accident. Instead, they were purposefully placed in strategic locations by a group of people who were under pressure from frequent warfare.

For Haas, the positioning of settlements in Long House Valley shows that all five of the valley’s villages communicated with one another and had formed something of an alliance. But if the villages weren’t fighting amongst themselves, who was attacking them? The evidence that Haas uncovered points to other groups of Kayenta Anasazi living nearby as the enemies of the Long House inhabitants.

The residents of Kletha Valley, located just to the east and south of Long House Valley, may have been one of these enemy groups. A 15 kilometer no-man’s land, devoid of any settlements, separated the two valleys. And the carefully preserved line-of-sight connections between the Long House villages do not extend to settlements in Kletha Valley. Warfare with Kletha residents could also help to explain why the southern portion of Long House Valley, which borders Kletha Valley, was abandoned in the early 13th century. Other Kayenta Anasazi groups living further away at sites like Canyon de Chelly and Mesa Verde may have also raided the villages of Long House Valley. As you might expect, the cycle of environmental degradation and warfare that consumed the Kayenta Anasazi during the late 1200's proved unsustainable, and they abandoned their ancestral homelands by 1300 AD. There is still some debate over exactly where they went, but many present-day Native American groups including the Hopi and Zuni trace their ancestry to the Anasazi.

What does a war look like a thousand years after it ends? Before Jonathan Haas's work in Long House Valley, most archaeologists had failed to think about how they might answer this question. The Kayenta Anasazi never had a written language, so we can't very well open a history book and read about their lives, their wars, their politics and beliefs. Instead, we are left to piece together their story using what they did leave behind – ruined stone buildings, pottery, stone tools, the remains of their own bodies. And this is exactly what Haas did – he showed that archaeology can be used to look into the past to understand when, why, and how warfare developed. In the years since this work, the anthropology of war has become a more and more important area of study. Primatologists, cultural anthropologists, archaeologists, psychologists, and many others have all weighed in on the question of where human warfare came from, and what this means for us today.

As for what the story of the Kayenta Anasazi can tell us today – the people of Long House Valley lived in peace for centuries before warfare became a persistent threat to their everyday lives. Their story challenges the conventional wisdom that warfare has been a constant throughout human history. Instead it can emerge under specific, complicated conditions, which in this case included drought, famine, and the founding of more concentrated, politically organized communities.


Haas, Jonathan, Stress and Warfare Among the Kayenta Anasazi of the Thirteenth Century. Chicago: Chicago Natural History Museum. 1993. Full Text Available at:

Further Reading:

Haas, Jonathan, Warfare and the Evolution of Culture, in Archaeology At the Millennium. 2007, Part III, 329-350, DOI: 10.1007/978-0-387-72611-3_9 Full Text Available at: (pdf)

About the Author: Dan Bailey is a chemist at a pharmaceutical company in Boston. He recently graduated from Brown University with degrees in anthropology and chemistry. His experience with archaeology includes working on excavations at the First Baptist Church in Providence, R.I., and at La Milpa, a Classical Maya site in Belize. He blogs at Smells Like Science.

The views expressed are those of the author and are not necessarily those of Scientific American.