Wakan Tanka was known as the great spirit and creator of the universe. There were other deities as well; Nakotas were a very prayerful people. Access to the supernatural world was provided in part by guardian spirits obtained through quests and in dreams. From the eighteenth century on, Nakotas performed the Sun Dance.
The Yanktons were organized into eight bands. The upper division Yanktonais consisted of six bands, and the Hunkpatinas had seven bands. The governing band council was composed of band chiefs and clan leaders. The Seven Council Fires met approximately annually to socialize and discuss matters of national importance. Nakota bands were composed of patrilineal clans.
Small villages were located near lakes and rice swamps when the people lived in the Wisconsin–Minnesota area. In the summer they lived in large houses of timbered frames with pitched roofs and bark-covered sides, whereas in the winter they lived in small mat-covered houses. From the mid- to late eighteenth centuries, the Yanktonais lived in earth lodges like the Arikaras, as well as in teepees
While still in the Great Lakes region, women grew corn, beans, and squash. People also gathered wild rice and ate turtles, fish, and dogs. Large and small game, especially buffalo, which roamed the area in small herds, was also an important food source. With the westward migration, buffalo became increasingly important, although men still hunted deer, elk, and antelope. Women also grew some corn, beans, and squash along river bottom-lands and gathered fruits and berries.
As the Missouri River trade developed, the Yanktons controlled the catlinite, or red pipestone, quarry in southwest Minnesota, supplying its clay to most of the northern Plains groups. During the early nineteenth century, the Yanktonais traded along the Jones River, acting as intermediaries for British goods between the Sisseton and Wahpeton Dakotas and the Tetons farther west.
Nakotas plied the northern Woodlands in birch-bark and dugout canoes. On the Plains, horses replaced dogs as travois carriers around 1760. They also used round bull boats when crossing water. Most clothing was made from buckskin. In the Woodlands, the people wore breechclouts, dresses, leggings, and moccasins, with fur robes for extra warmth. On the Plains, they decorated their clothing with beads and quillwork in geometric and animal designs.
Dakota-Lakota-Nakota speakers ranged throughout more than 100 million acres in the upper Mississippi region, including Minnesota and parts of Wisconsin, Iowa, and the Dakotas, in the sixteenth to early seventeenth centuries. At this time the Yanktons and Yanktonais were one tribe, the Assiniboines having separated from the Yankton/Yanktonais, probably by the midsixteenth century.
French explorers encountered Eastern group tribes around Mille Lacs, Minnesota, in the late seventeenth century. Shortly afterward, the latter probably became directly involved in the fur trade. But conflict with the Crees and Ojibwas, who were well armed with French rifles, in addition to the lure of great buffalo herds to feed their expanding population, induced bands to begin moving west onto the Plains.
The Yanktons and Yanktonais separated near Leech Lake in the late seventeenth century. The Yanktons had moved out of the northern Woodlands and onto the southern prairies (near the pipestone quarries of southwest Minnesota and then west of the Missouri in northwest Iowa) by the early eighteenth century. A hundred years later, the Yanktons ranged north and northwest into Minnesota and South Dakota.
Meanwhile, the Yanktonais left their homes in Mille Lacs by the early eighteenth century to follow Teton tribes west, making winter villages on the James River (South Dakota) at least as early as 1725. They acquired horses in the mid- to late eighteenth century. By the early nineteenth century they were hunting buffalo between the Red and the Missouri Rivers and north to Devil's Lake.
A general Yankton decline set in during the 1830s. Its causes were smallpox, the growing scarcity of game, and war, particularly with the Pawnees, Otoes, and Omahas. Yanktons ceded their Iowa lands (2.2 million acres) to the United States in 1830 and 1837 treaties and ceded over 11 million acres in 1858. They did retain a 430,000-acre reservation near Fort Randall, South Dakota. They also claimed the 650-acre Pipestone Reservation in Minnesota.
By 1860, the Yanktons had ceded all of their remaining lands. Most moved to the Yankton Reservation in South Dakota; others went to the Crow Creek and Lower Brûlé Reservations in South Dakota and to the Fort Totten (now Devil's Lake) Reservation in North Dakota. The Yanktonais ceded their remaining lands in 1865. They were removed to a number of reservations, including Standing Rock (South Dakota), Devil's Lake (North Dakota), Crow Creek (South Dakota), and Fort Peck (Montana). In 1866 they replaced the Santees at Crow Creek when the latter were moved to Nebraska. The Yanktons sold the Pipestone Reservation in 1929 for almost $330,000 plus guarantees of Indian access.