In this part of America, the first documented European contact with American Indians occurred in the late 1600s when Jesuits established missions along the rivers near here, and Padre Eusebio Kino and fellow missionaries first visited the Tucson Basin in 1692. From 1692 to 1821, the Spanish established more than two dozen missions and presidios in southern Arizona and northern Sonora, Mexico, introducing new forms of religion, dress, speech, mining, domestic animals, agricultural crops, tools, and diseases. Mexican independence in 1821 brought more change as more Mexican farmers, ranchers, and miners moved into southern Arizona and took some of the best land for farms and ranches. The United States gained this territory through the Gadsden Purchase of 1853, and American Indian people then lived under a third flag in as many centuries. After the American Civil War, southern Arizona boomed with prospecting and mining; many miners searched for gold with limited success, but copper became Arizona's most important metal during the twentieth century. Large-scale mining operations such as the Silverbell Mine could be seen across southern Arizona, and although the Tucson Mountains did not contain rich ore deposits, prospectors worked more than 140 claims in the Tucson Mountain District of the park. Despite these changes, American Indians of the Southwest continue to practice many traditional activities, including the annual saguaro fruit harvest on park land by the Tohono O'Odham people.