Moody County was part of the domain of the Dakota (Sioux) Indians, with a trading post traditionally at the Great Bend as early as 1763, and Joseph LaFramboise in 1822 and Philander Prescott in 1832-33 certainly had posts there. The portion east of the Big Sioux was ceded by the Santee Sioux in 1851, and the portion west by the Yankton Sioux in 1858. Its first settlement, at Flandreau, was established in 1857 but abandoned because of Indian pressure in 1858. Flandreau was named for Charles E. Flandreau (1828-1903). Until 1873, the county's south half was part of Minnehaha and its north half of Brookings County. Named for Gideon C. Moody (1832-1906), a territorial legislator and first U.S. Senator, its first permanent settlers were 25 Christian Santee Sioux Indians who took homesteads in 1869. Among them were Old Flute, All-Over-Red, Iron Old Man, the pastor, Iron Dog, and Big Eagle, who were along the river, as were James Jones and L.M. Hewlett, when in September 1869 Eli P. Drake surveyed the county. Shortly thereafter Charles K. Howard set up a trade store on the Sioux at Flandreau, where the Pettigrew Brothers, surveyors and enterprising pioneers, had the town established by 1872. The county was organized by David Fairbault, Harry Stoughton, and Edward Pierce on August 30, 1873, and Flandreau was soon named county seat. By 1880, despite grasshoppers, drought, and blizzards, there were 3,915 people in the county. The railroad reached Flandreau on 1 January 1880. Riggs Institute of 1892 became the Flandreau Indian School, the center of a considerable Indian community whose church building dates back to 1872.