The people whom the Spanish called the Opas or the Cocomaricopas were one of several small Yuman tribes (including the related groups—the Halchidomas, Kahwans, Kavelchadoms, and the Halyikwamais) who lived along the lower Colorado River. Contact with the Spanish was minimal and sporadic. By the early eighteenth century, these peoples had relocated up the Gila River, owing to an escalation of attacks by the Quechans and Mojaves. The Pimas offered them land and protection, and the two groups soon formed a confederation. By the early nineteenth century, the Pee-Posh had all but absorbed the smaller tribes.
The Pima–Maricopa confederacy went a long way toward making non-Indian settlement of that part of the desert possible, protecting Anglos from Apaches, starvation, and thirst. For example, the Indians used much of their surplus wheat to provide food for the so-called forty-niners on their way to California. (By 1870, their wheat production had reached 3 million pounds, an achievement that aroused the wrath of Anglo wheat farmers.) The Indians also sold wheat to the U.S. Army. Beginning in the 1840s, and continuing throughout the century, epidemics took a heavy toll on the Indian population. In 1857, the confederacy decisively defeated the Quechans and Mojaves at Maricopa Wells, marking the last major formal battle between Indian nations in the Southwest.
In recognition of its alliance with the confederation, the U.S. government established a reservation on the Gila River in 1863 for the Pimas and the Pee-Posh. However, river water levels soon began to fall to such low levels as a result of upstream diversions by non-Natives that a group of Indians moved to the confluence of the Gila and Salt Rivers. Now known as Laveen, this community was first called Maricopa Colony. Halchidoma descendents soon relocated to the Salt River, around the present site of Lehi. In 1879, the original reservation was enlarged, and the Salt River Reservation was established.
During that decade several factors conspired to ruin the Indians' thriving economy: a decline in rainfall, a doubling of the population, and, in particular, huge diversions of Gila River water by non-Indians. By the 1880s, Indian crops routinely failed and famine threatened. Many Pimas and Pee-Posh were forced into the wage economy at the lowest levels. With the loss of the river, the heart of their culture also disappeared. The U.S. government continued to ignore the key problem of water rights, and Pima and Pee-Posh impoverishment continued well into the twentieth century.
In the late nineteenth century, the Bureau of Indian Affairs (BIA) began a campaign to assimilate local Indians. With its blessing, the Presbyterian Church became very active at Gila River, beginning a day school and in general imposing a religious structure on the tribes. The issue of Christianity proved to be a very divisive one on the reservation. In 1914, allotment hit both reservations (against active Indian opposition), scattering the people and further disrupting community life. In 1926, the BIA formed a Pima Advisory Council in an effort to create a formal body that spoke for the tribe. In 1934, the Pimas created a constitution, which was revised by the Pima and Pee-Posh community two years later.
By 1930, non-Native water diversions had effectively ended Gila River surface water flowing to the Pee-Posh. Rather than redress the situation, the BIA forced the Indians to use brackish well water. This water was suitable only for growing cotton and some grains, however, and the people could no longer grow edible crops. Several other factors worked to cancel any benefits that might have come with the well water, including a dependency of Indians on wage work, continued ongoing water shortages, and the hated allotments (heirships), which had destroyed their effective land base.
In 1934, the Pimas and the Pee-Posh accepted the Indian Reorganization Act (IRA) and formed the Gila River Indian Community. Following World War II, many Pee-Posh (encouraged by the BIA's relocation program) moved away from the reservation. For years outsiders thought that the Pee-Posh had died out and become a subgroup of the Pima Indians.
Nominal village chiefs exerted little influence. Recognized specialists had the true authority, as curers, calendar stick keepers, singers, potters, and dancers. All obtained their power from dreams.
Entire villages moved when someone died, after the body, residence, and possessions had been burned. Special singers sang elaborate song cycles for funerals and transmitted legends, such as ancestral wanderings or conflicts with other groups. Girls celebrated a special puberty ceremony, after which they were tattooed. Both sexes cultivated a high tolerance of pain. As was true for other River Yumans, farming, including ownership of the farm site, was essentially an individual activity. Boundary disputes were solved by mediation or by controlled fighting. The Pee-Posh recognized patrilineal clan as well as village divisions.
Flattened-dome houses were built with a frame of mesquite or cottonwood uprights and covered with willow ribs and arrowweed thatch. Walls were packed with earth. Rectangular ramadas often adjoined the houses. All dwelling entrances faced east. Other structures included storage sheds, woven basket granaries, and sweat lodges.
The Pee-Posh used floodwater agriculture in their farming. Their staples were mesquite beans and corn. Men planted and cultivated, and women harvested. Much food was also gathered, including seeds, berries, nuts, cactus fruit, honey, caterpillars, and beans. The people also ate jackrabbits and fish (caught with nets or bare hands).