1838. Dr. Joseph N. Nicollet, accompanied by John C. Frémont, visits the coteau region of eastern South Dakota, mapping and naming the lakes.
1839. Nicollet and Frémont again visit South Dakota, coming up the river to Fort Pierre, thence passing over to James River, and finally to the Minnesota.
- Father Pierre John De Smet visits the renegade band of Wakpekuta Sioux under Wamdesapa, to try to effect a peace between them and the Potawatomies of central Iowa.
1840. Dr. Stephen R. Riggs, celebrated missionary from Minnesota River, visits Fort Pierre and preaches first sermon in Dakota.
1842. Audubon, the naturalist, visited the section upon a professional trip and observed and noted most of the birds and animals.
- Father Alexander Ravonx visits Fort Pierre and baptizes many Indians and half bloods.
1845. Father Ravoux visits Fort Vermilion.
1847. Mrs. Joseph La Barge comes to Fort Pierre, with her husband, Captain La Barge of the steamboat Martha. First white woman to visit South Dakota. The Martha attacked by Yankton Indians at Crow Creek.
1849. Inkpaduta, son of the renegade Wamdesapa, massacres his cousin Wamundiyakapi and seventeen other Wakpekutas.
1851. Father De Smet visits the Teton Sioux.
- Santee Sioux relinquish title to all land east of Big Sioux River by treaty of Traverse des Sioux.
1855. Government buys Fort Pierre. General W. S. Harney, after battle of Ash Hollow, in Nebraska, brings army of twelve hundred men to Pierre. Lieutenant G. K. Warren, afterward famous in Civil War, examines and makes topographical survey of much of South Dakota.
1857. Settlement begun at Sioux Falls, Flandreau, and Medary.
- "The Noble Road" built across the state from Lake Benton to Crow Creek.
- Fort Randall completed and occupied.
- Inkpaduta, the renegade, massacres forty-two settlers at Spirit Lake, Iowa, and retreats into South Dakota with three white women captives.
