Their traditional territory lies between the Kiliwa on the south and the Kumeyaay and Cocopa on the north, and extending from San Vicente near the Pacific coast nearly to the Colorado River's delta in the east.

Numerous plants were exploited as food resources, notably including agave, yucca, mesquite, prickly pear, acorns, pine nuts, and juniper berries.

Animals used for food included deer, pronghorn, bighorn sheep, rabbits, woodrats, various other medium and small mammals, quail, fish, and shellfish.

These include the accounts of the maritime expedition led by Sebastián Vizcaíno; reports by late 18th and early 19th century observers, such as Luis Sales and José Longinos Martínez; and the studies of 20th century ethnographers, including Edward W. Gifford, Robert H. Lowie, Peveril Meigs, Philip Drucker, William D. Hohenthal, Roger C. Owen, Thomas B. Hinton, Frederic N. Hicks, Ralph C. Michelsen, Michael Wilken-Robertson, and Julia Bendímez Patterson.

Paipai traditional material culture included structures (rectangular thatched-roof houses, ramadas, and probably sweathouses), equipment for hunting and warfare (bows, cane arrows, war clubs, nets), processing equipment (pottery, basketry, manos and metates, mortars and pestles, cordage, stone knives, awls), clothing (rabbitskin robes, fiber sandals; buckskin aprons and basketry caps for women), and cradles.

More intensive and sustained contacts began in 1769 when the expedition to establish Spanish settlements in California, led by Gaspar de Portolà and Junípero Serra, passed through the western portions.