The Gila River forms in western New Mexico and flows west across southeastern, south-central, and southwestern Arizona; it changes directions as it progresses across the state, and defines specific areas and valleys.

The Gila Valley of Yuma County, Arizona is a small valley surrounding the Gila River at its confluence with the Colorado River, the Colorado being the border between California and Arizona, and locally southwest of Yuma – Baja California, and Sonora states, Mexico.

It is estimated that around 50,000–60,000 Huhugam people populated the Gila River Valley at the height of their "Classic Period" (around 1150–1450 CE).

[3] When the Pee-Posh (or Maricopa) tribe was driven out from the Yuman tribal people in the 1840s, they found refuge along the Gila River with the Pima.

President Franklin Pierce commanded soldiers posted near the newly acquired land to determine the new boundaries of the Arizona Territory.

During the expedition in Graham Country, General Carleton took note of a tactical location offering a wide open view of the Gila Valley where he would later establish Fort Goodwin.

The settlers quickly dug irrigation ditches along the banks of the Gila river and planted crops in the fertile soil.

[11] The emigration of ranchers from Texas to Arizona increased settlement populations and changed the dynamics of early communities in the Gila Valley.

In 1883, many polygamist families fled to Southern Arizona and Mexico in order to escape federal prosecution and imprisonment under the new Edmunds Tucker Law, which banned the practice of polygamy in the United States and its territories.

[13] A vast majority of the Mormon settlers primarily sustained themselves either by farming or working as freighters for the surrounding mines in Morenci and Clifton .

[17] A sawmill was built on nearby Mount Graham, along with a complicated network of flumes and cable tramways constructed to facilitate the transport of the wood down to the Gila River Valley.

Newly converted Mormons, especially from the Eastern United States and Europe, flocked to the Gila River Valley to claim land of their own.

[26] This debate over borders and boundaries was a point of contention for early settlers in the Gila Valley who did not have easy access to accurate maps.

[3] The new towns of Adamsville and Florence were built upstream from the Gila River Indian Reservation, leaving the Pima with little of the water they claimed as their legal right.

The situation worsened with the founding of the Mormon town of Safford and settlements in Solomonville, Duncan, Pima, and Thatcher—each of which required the construction of more canals.

The Pima called upon the US Army to intervene, and General Irvin McDowell brought the issue to President Rutherford B. Hayes’ attention.

Hayes stopped the sale of public land along the Gila River and greatly extended the reservation with an executive order in 1879.