The first significant contact of the Cocopah with Europeans and Africans probably occurred in 1540, when the Spanish explorer Hernando de Alarcón sailed into the Colorado River delta.

After the Mexican-American War, Cocopah lands were split between the U.S. and Mexico through the Mexican Cession resulting from the Treaty of Guadalupe Hidalgo.

Westward expansion in the 1840s and the discovery of gold in California in 1849 brought many migrants through the area near the mouth of the Colorado River and the Grand Canyon region.

The strategic importance of the river crossing was recognized by the U.S. government, and the United States Army established Camp Independence in 1850 to protect the entry route through the tribe's territories.

[3] The Cocopah agreed to join Garra's Tax Revolt of 1851, led by the Cupeño, to fight against the U.S. government alongside the Quechan and nearby Kumeyaay bands.

The Cocopah were joined by the Paipai, Kiliwa, and Kumeyaay, and prepared to fight alongside the Magonistas, as Jiménez smuggled US arms to Mexico with the support of the Industrial Workers of the World (IWW).

Jiménez carried out a campaign with the Cocopah, Paipai, and Kiliwa armies from El Rosario to Ensenada, raiding small towns and looting Chinese-Mexican businesses.