Native Americans hunted in the Badlands for over 11,000 years. The earliest Indigenous people were the Paleo-Indians. These hunter-gatherers were skilled at harvesting bison and mammoths. Next came the Arikara, a semi-nomadic tribe. In the late 18th century, the Teton Sioux or Lakota arrived. They were the dominant tribe by 1840. Their large presence sparked several conflicts with the U.S. Amy including the Great Sioux War in 1876. By 1877, the U.S. government forced the Sioux into reservations. Since 1976, the South Unit of Badlands National Park is Tribal Trust land to be used by the Oglala Sioux. The tribe’s Pine Ridge Indian Reservation in southwest South Dakota consists of almost 3.5 million acres.