The document discusses the history of control over the Trans-Missouri West from 1541 to the early 1800s by Spain, France, Britain, and the United States. It then summarizes the objectives of the Lewis and Clark Expedition and several other expeditions in the early 1800s. Next, it outlines the establishment of missions in the region by various Protestant denominations starting in the 1830s to respond to issues like alcohol abuse among Native Americans. It concludes by noting the influential roles of two missionaries, Samuel Hinman and Pierre De Smet, in treaty negotiations with Lakota tribes in 1868.