For more than a century, archaeologists have pondered the disappearance of the Hohokam from the Sonoran Desert. Sometime around A.D.1450, only decades before Columbus arrived in the New World, the Hohokam abandoned their major villages in the Salt and Gila River valleys, including Pueblo Grande. Why, after centuries of successfully cultivating the arid desert, did their society collapse? There have been many competing theories including soil salinization, disease, warfare, floods, droughts, and climatic changes. None or all could be correct; all are still under investigation.
Salinization of the soil has been a common explanation for the demise of the Hohokam. It was once thought that through the constant irrigation of their fields, the Hohokam were forced to abandon them because of excessive salt deposits (salinization) in the soil, a result of constantly soaking the fields with highly alkaline water. Historically, however, it is known that irrigated fields in the Salt River Valley became salinated after a mere 50 years of irrigation. Historic farmers quickly learned to flush their fields in order to remove salts, and to let their fields lie fallow for periods of time to allow the soil to rejuvenate itself. The Hohokam would have had to deal with this same soil problem soon after settling in the Salt River Valley. The fact that the Hohokam practiced irrigation agriculture successfully for more than 1,000 years indicates that they had addressed this problem. Nonetheless, it is possible that during the Classic period, the Hohokam did not manage their fields as well as they had during previous periods, causing the soil to become too saturated with salt.
Climate: Droughts and Floods
Some archaeologists have proposed that changing climatic conditions forced the Hohokam to move elsewhere. Analysis of tree-ring and stream flow data have shown that the Hohokam experienced massive floods in A.D. 1358 and again in the early 1380s, which in all probability damaged their canal irrigation systems. These floods appear to have been interspaced with periods of drought. But the Hohokam had built and repaired canals for hundreds of years. They had experienced flooding in the past, such as a major flood in A.D. 899, and had recuperated from its devastating consequences. Why were they not able to recover from the floods of the 14th century?
Other theories have suggested that warfare and raids by other groups, including the Apache, led to the disappearance of the Hohokam from the desert. Other than the existence of a series of possible hilltop fortifications, little evidence has arisen out of the archaeological record to support this idea. Furthermore, the timing of the initial appearance of the Apache and Navajo in the Southwest is still unclear.
Another factor that has been proposed for the collapse of the Hohokam involves diseases. During the mid-16th century, the Spanish brought diseases from Europe that killed hundreds of thousands of American Indians in Mesoamerica and the eastern United States. But the Hohokam cultural collapse appears to have occurred before the Spanish arrived in the New World. On the other hand, if local plagues or water borne diseases were introduced into the Hohokam's enormous canal system, the diseases could have spread quickly among the close-knit villages. However, no clear evidence of disease has been found, such as mass graves or large cremation areas, indicating that the Hohokam experienced epidemics.
Migration and Overpopulation
Some archaeologists have suggested that as a result of declining rainfall, neighboring cultures from the north and east abandoned their homes and settled among the Hohokam during the 1300s. This increased population would have dangerously overextended the available resources that the Hohokam had kept in balance for generations. The population of Pueblo Grande probably reached its peak in the Classic period, with as many as 1,000 people living in the village. Studies of burials excavated from the site during this time period indicate that the population was suffering from malnutrition despite their utilization of all available resources, including the intensive harvesting of fish from the Salt River and local irrigation canals. This evidence suggests that the Hohokam at Pueblo Grande may have exceeded the carrying capacity of the desert which, combined with other factors, eventually forced the Hohokam to abandon the village.
The Hohokam Today
A number of archaeologists argue that although the Hohokam society did indeed collapse, the Hohokam never completely abandoned the Sonoran Desert. Instead, they believe that the American Indian groups living there at the time of the Spaniards' arrival in central Arizona, around A.D. 1694, are the descendants of the Hohokam. Many ancient legends of the Pima (Akimel O'odham) frequently mention the Hohokam. In one version of the Pima oral traditions, a Pima revolt, led by their culture hero Elder Brother, destroyed all the Hohokam platform mound villages. Because Pueblo Grande was so powerful, the Pima had to enlist the aid of shamans and one of them used his power of thunder to destroy the village.
Today, it is generally believed that the Pima and the Tohono O'odham (Papago) of southern Arizona are descendants of the Hohokam. However, oral traditions of the Hopi Indians of northern Arizona state that a number of Hopi clans once lived in southern Arizona before migrating to their present location. Furthermore, some archaeologists have noted similarities between the Hohokam culture and Yuman groups in southwestern Arizona.
If the Hohokam never left, why then did they abandon most of their villages in the Salt and Gila River valleys, including Pueblo Grande, around A.D. 1450? Perhaps the most plausible theory is that Hohokam society collapsed through internal conflicts triggered by environmental pressures on a population that had met or exceeded the carrying capacity of the land. Archaeologists estimate that there may have been from 24,000 to more than 50,000 Hohokam people living in the Sonoran desert before the Hohokam culture collapsed. The floods of the late-14th century may have severely damaged the Hohokam canal systems which supported such large numbers of people in an arid environment. This, in turn, weakened the control and authority of the secular or theocratic elite. Pima oral traditions tell of how their forefathers overthrew the rulers of the platform mound villages, mentioning Pueblo Grande specifically, because they had grown arrogant. This is surely a sign of social unrest. With new archaeological evidence coming to light almost daily, it is now known that the Hohokam did not simply vanish or abandon their villages overnight, but instead their cultural collapse appears to have been an extended process lasting several generations. But whatever the cause and however long it took, more than 1,000 years of occupation at Pueblo Grande came to an end in the mid-15th century.