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.

Edwin Thompson Denig (1812-1858) was a fur trader on the Upper Missouri for twenty-five years.