Origins During the period from 700 to 1130 CE (
Pueblo I and
II Eras), the population grew fast due to consistent and regular rainfall which supported agriculture. Studies of skeletal remains show increased fertility rather than decreased mortality. However, this tenfold population increase over a few generations was probably also due to migrations of people from surrounding areas. Innovations such as pottery, food storage, and agriculture enabled this rapid growth. Over several decades, the Ancestral Puebloans culture spread across the landscape. Ancestral Puebloan culture has been divided into three main areas or branches, based on geographical location: •
Chaco Canyon (northwest New Mexico) •
Kayenta (northeast Arizona), and • Northern San Juan (
Mesa Verde and
Hovenweep National Monument) (southwest Colorado and southeastern Utah) DNA evidence confirms the ancestors of the inhabitants of
Picuris Pueblo once lived in
Chaco Canyon, now a
UNESCO World Heritage Site. Modern Pueblo oral traditions hold that the Ancestral Puebloans originated from , where they emerged from the
underworld. For unknown ages, they were led by chiefs and guided by spirits as they completed vast migrations throughout the continent of North America. They settled first in the Ancestral Puebloan areas for a few hundred years before moving to their present locations.
Migration from the homeland , Chaco Canyon The Ancestral Puebloans left their established homes in the 12th and 13th centuries. The main reason is unclear. Factors discussed include global or regional climate change, prolonged drought,
environmental degradation such as cyclical periods of
topsoil erosion or deforestation, hostility from new arrivals, religious or cultural change, and influence from
Mesoamerican cultures. Many of these possibilities are supported by archaeological evidence. Current scholarly consensus is that Ancestral Puebloans responded to pressure from
Numic-speaking peoples moving onto the Colorado Plateau, as well as climate change that resulted in agricultural failures. The archaeological record indicates that for Ancestral Puebloans to adapt to climatic change by changing residences and locations was not unusual. Early Pueblo I Era sites may have housed up to 600 individuals in a few separate but closely spaced settlement clusters. However, they were generally occupied for 30 years or less. Archaeologist Timothy A. Kohler excavated large Pueblo I sites near
Dolores, Colorado, and discovered that they were established during periods of above-average rainfall. This allowed crops to be grown without requiring irrigation. At the same time, nearby areas that suffered significantly drier patterns were abandoned. Ancestral Puebloans attained a cultural "Golden Age" between about 900 and 1150. During this time, generally classed as Pueblo II Era, the climate was relatively warm and rainfall mostly adequate. Communities grew larger and were inhabited for longer. Highly specific local traditions in architecture and pottery emerged, and trade over long distances appears to have been common.
Domesticated turkeys appeared. After around 1130, North America had significant climatic change in the form of a 300-year period of aridity called the Great Drought. This also led to the collapse of the
Tiwanaku civilization around
Lake Titicaca in present-day Bolivia. The contemporary
Mississippian culture also collapsed during this period. Confirming evidence dated between 1150 and 1350 has been found in excavations of the western regions of the
Mississippi Valley, which show long-lasting patterns of warmer, wetter winters and cooler, drier summers. , Utah In this later period, the Pueblo II became more self-contained, decreasing trade and interaction with more distant communities. Southwest farmers developed irrigation techniques appropriate to seasonal rainfall, including soil and water control features such as check dams and terraces. The population of the region continued to be mobile, abandoning settlements and fields under adverse conditions. There was also a drop in
water table due to a different cycle unrelated to rainfall. This forced the abandonment of settlements in the more arid or overfarmed locations. Evidence suggests a profound change in religion in this period. Chacoan and other structures constructed originally along astronomical alignments, and thought to have served important ceremonial purposes to the culture, were systematically dismantled. Doorways were sealed with rock and mortar. Kiva walls show marks from great fires set within them, which probably required removal of the massive roof – a task which would require significant effort. Habitations were abandoned, and tribes divided and resettled far. This evidence suggests that the religious structures were abandoned deliberately over time. Pueblo
oral history holds that the ancestors had achieved great spiritual power and control over natural forces. They used their power in ways that caused nature to change and caused changes that were never meant to occur. Possibly, the dismantling of their religious structures was an effort to symbolically undo the changes they believed they caused due to their abuse of their spiritual power, and thus make amends with nature. Most modern Pueblo peoples (whether
Keresans,
Hopi, or
Tanoans) assert the Ancestral Puebloans did not "vanish", as is commonly portrayed. They say that the people migrated to areas in the southwest with more favorable rainfall and dependable streams. They merged into the various Pueblo peoples whose descendants still live in Arizona and New Mexico. This perspective was also presented by early 20th-century anthropologists, including
Frank Hamilton Cushing,
J. Walter Fewkes, and
Alfred V. Kidder. Many modern Pueblo tribes trace their lineage from specific settlements. For example, the
San Ildefonso Pueblo people believe that their ancestors lived in both the Mesa Verde and the Bandelier areas. Evidence also suggests that a profound change took place in the Ancestral Pueblo area and areas inhabited by their cultural neighbors, the
Mogollon. Historian
James W. Loewen agrees with this oral tradition in his book,
Lies Across America: What Our Historic Markers and Monuments Get Wrong (1999). No academic consensus exists with the professional archeological and anthropological community on this issue.
Warfare Environmental stress may have caused changes in social structure, leading to conflict and warfare. Near
Kayenta, Arizona, Jonathan Haas of the Field Museum in Chicago has been studying a group of Ancestral Puebloan villages that relocated from the canyons to the high mesa tops during the late 13th century. Haas believes that the reason to move so far from water and arable land was a defense against enemies. He asserts that isolated communities relied on raiding for food and supplies, and that internal conflict and warfare became common in the 13th century. This conflict may have been aggravated by the influx of less settled peoples, Numic-speakers such as the
Utes,
Shoshones, and
Paiute people, who may have originated in what is today California, and the arrival of the
Athabaskan-speaking Diné who migrated from the north during this time and subsequently became the
Navajo and
Apache tribes most notably. Others suggest that more developed villages, such as that at Chaco Canyon, exhausted their environments, resulting in widespread deforestation and eventually the fall of their civilization through warfare over depleted resources. A 1997 excavation at
Cowboy Wash near
Dolores, Colorado found remains of at least 24 human skeletons that showed evidence of violence and dismemberment, with strong indications of
cannibalism. This modest community appears to have been abandoned during the same time period. Other excavations within the Ancestral Puebloan cultural area have produced varying numbers of unburied, and in some cases dismembered, bodies. In a 2010 paper, Potter and Chuipka argued that evidence at
Sacred Ridge site, near
Durango, Colorado, is best interpreted as warfare related to competition and
ethnic cleansing. This evidence of warfare, conflict, and cannibalism is hotly debated by some scholars and interest groups. Suggested alternatives include: a community suffering the pressure of starvation or extreme social stress, dismemberment and cannibalism as religious ritual or in response to religious conflict, the influx of outsiders seeking to drive out a settled agricultural community via calculated atrocity, or an invasion of a settled region by nomadic raiders who practiced cannibalism. ==Cultural distinctions==