Historically, the O'odham inhabited an enormous area of land in the southwest, extending South to Sonora, Mexico, north to Central Arizona (just north of Phoenix, Arizona), west to the Gulf of California, and east to the San Pedro River. This land base was known as the Papagueria and it had been home to the O'odham for thousands of years.
From the early 18th Century through to the present, the O'odham land was occupied by foreign governments. With the independence of Republic of Mexico, O'odham fell under Mexican rule. Then, in 1853, through the Gadsden Purchase or Treaty of La Mesilla, O'odham land was divided almost in half, between the United States of America and Mexico.
The division of O'odham lands has resulted in an artificial division of O'odham society. O'odham bands are now broken up into 4 federally recognized tribes: the Ak Chin Indian Community, the Tohono O'odham Nation, the Gila River Indian Community, and the Salt River Indian Community (Pima Maricopa). Each band is now politically and geographically distinct and separate. The remaining band, the Hia C-eḍ O'odham, are not federally recognized, but reside throughout southwestern Arizona. All of the groups still speak the O'odham language, which derives from the Uto-Aztecan language group, although each group has varying dialects.