It is thought that the first people to make their way into what is now South Dakota came across a land bridge from Asia, through Alaska, and then migrated south. They traveled to North America sometime between 15,000 and 20,000 years ago. Evidence of our first peoples, Paleoindians, here in South Dakota can be traced to around 11,500 years ago.
The Clovis peoples were hunters and gatherers of the Old Stone Age. Their weapons were stone and bone and they lived with and hunted giant bison, mammoths, camels, and saber-toothed tigers. Evidence of their life on the plains was uncovered on what is now the Pine Ridge Reservation . The Clovis peoples appeared just as the ice age was coming to a close. As ice age animals became extinct, hunting tools changed and a new era of hunters, called the Folsom hunters, appeared. Folsom spear points, longer and finer than Clovis points, have been found in South Dakota, though no campsites have been located. It was with these spear points that the long-lasting tradition of the bison hunt began.
Archaeological evidence has determined that about 7,000 years ago, the climate of South Dakota began to change. It had been relatively warm and comfortable, but it got much drier, with frequent droughts. Hunting expanded to include smaller game and plant foods were incorporated into the people’s diet. Communities were very small. By 3,000 years ago, the weather on the plains was about the same as it is today. Bison hunts by then had become fairly sophisticated with larger bands of Indians coming together to use traps and drives to kill larger numbers of animals. It was possible to sustain more people in a single community as the ability to procure food improved. This period, as tribes became larger, was known as the Woodland period. In the west the woodland hunters are believed to be the predecessors to the Shoshone, Kiowa, Crow, and the Cheyenne. Over time, spears gave way to the bow and arrow, pottery came into use, and the first traces of true agricultural practices appear around A.D. 900. Between A.D. 1250 and 1450, an agricultural people migrated from southern Minnesota. These people, believed to be the predecessors to the Mandan, Arikara, and Hidatsa, were planting corn, beans, squash, and sunflowers.
One of the most successful early tribes of the Dakotas were the Arikara. The Arikara migrated up the Missouri River Basin from Kansas and Nebraska in the 1500s. They settled in central South Dakota, near the current location of Pierre. The Arikara built earth lodges and lived in small villages. At one time, it is believed that there were as many as 32 villages and as many as 4,000 warriors scattered along the river. The Arikara were non-nomadic and had an advanced system of trade with other tribes. They were responsible for many of the horses that were traded to the Teton Sioux, initially located to the east. Horses were brought up from the southwest by the Kiowa, Arapahoe, Commanche, and Cheyenne, and the Arikara would travel to the Black Hills  on their hunting trips and pick them up for trading with other tribes.
The earliest record of the Sioux people, so closely entwined with the history of South Dakota, is from 1640, as recorded by French priests. At the time, the Sioux (so named by the Chippewa, who were French allies) were living near the headwaters of the Mississippi River. They called themselves the Dakota. There were seven different divisions of the Dakota Nation, one of which was the Teton Sioux, or Lakota. The Teton Sioux division, in turn, was comprised of seven tribes, which include the Oglala, Brule, Two Kettle, Sans Arc, Blackfoot, Hunkpapa, and Minneconjou. It was the Oglala Lakota who are recorded as being the first of the Teton Sioux to discover the Black Hills, in the late 1700s. At that time, the Black Hills were occupied by the Cheyenne. The Brule were the next to move west, settling south of the Badlands. Between 1776 and 1825, life was good for the tribes in their new location. Guns and horses had been added to their lifestyle; tipis replaced the stationary dwellings they occupied in the east; and game, particularly bison, was plentiful.