Cult, as used in this book, means a system of religious belief and worship, especially the rites and ceremonies employed in such worship. The present book treats of the cults of a few of the Siouan tribes—that is, with two exceptions, of such tribes as have been visited by the author. "Siouan" is a term originated by the Bureau of Ethnology. It is derived from "Sioux," the popular name for those Indians who call themselves "Dakota" or "Lakota," the latter being the Teton appellation. "Siouan" is used as an adjective, but, unlike its primitive, it refers not only to the Dakota tribes, but also to the entire linguistic stock or family. The Siouan family includes the Dakota, Assiniboin, Omaha, Ponka, Osage, Kansa, Kwapa, Iowa, Oto, Missouri, Winnebago, Mandan, Hidatsa, Crow, Tutelo, Biloxi, Catawba, and other Indians.

James Owen Dorsey was an American ethnologist, linguist, and Episcopalian missionary in the Dakota Territory, who contributed to the description of the Ponca, Omaha, and other southern Siouan languages. He worked for the Bureau of American Ethnology of the Smithsonian Institution from 1880-1895, when he died young of typhoid fever. He became known as the expert on languages and culture of southern Siouan peoples, although he also studied tribes of the Southwest and Northwest.