Edwin Thompson Denig, for more than twenty years a fur trader on the Upper Missouri and married to an Assiniboine woman, was an acute and objective observer of Indian manners and customs. He assisted Audubon and the Culbertsons in collecting Missouri River fauna, supplied information on the Indians to Father De Smet, who encouraged him to write, and provided Henry Schoolcraft with an Assiniboine vocabulary as well as a detailed "Report on the Indian Tribes of the Upper Missouri," which was not published until 1930, seventy-six years after it was written, and then only in parts.

Denig's writings on the Sioux, Arickaras, Assiniboines, Crees, and Crows, comprising the Denig manuscript in the Missouri Historical Society, are published together for the first time in this book. The manuscript long had been referred to as the "Culbertson Manuscript" because it had been purchased from a descendant of the fur-trader naturalist Alexander Culbertson. But in 1949, handwriting experts identified it as the work of Denig.

Edwin Thompson Denig entered the fur trade on the Upper Missouri River in 1833. As husband to the daughter of an Assiniboine headman and as a bookkeeper stationed at Fort Union, Denig became knowledgeable about the tribal groups of the Upper Missouri and was consulted for information on them by several noted investigators of Indian culture. When Denig was asked to respond to a circular by Henry Rowe Schoolcraft, he didn't simply rely on his own knowledge of the Assiniboines, but instead interviewed his subjects ""for an entire year, until satisfactory answers [had] been obtained.""Denig's manuscript, which he probably finished in 1854, remained unpublished until 1930, when J. N. B. Hewitt edited it for publication in the Smithsonian Bureau of American Ethnology's Forty-sixth Annual Report. This edition, featuring an introduction by David R. Miller, provides a complete ethnology of the Assiniboine Indians, including information on their history, tribal organization and government, religion, manners and customs, warfare, dances, and language.

Edwin Thompson Denig entered the fur trade on the Upper Missouri River in 1833. As husband to the daughter of an Assiniboine headman and as a bookkeeper stationed at Fort Union, Denig became knowledgeable about the tribal groups of the Upper Missouri. By the 1840s and 1850s, several noted investigators of Indian culture were consulting him, including Audubon, Hayden, and Schoolcraft. Not content to drawn on his own knowledge, he interviewed in company with the Indians for an entire year until he had obtained satisfactory answers.