On the move due to pressure from eastern and midwestern tribes moving west due to white encroachment, the Crow may have settled in the Yellowstone Valley only a few decades before the arrival of Lewis and Clark. Some time prior to the mid-17th century, the Hidatsa leader No-Vitals led a large number of Hidatsa west into the Yellowstone River valley of south-central Montana, where the tribe lived on the plains, by the river, and in the nearby Big Horn, Pryor, and Wolf Mountains. The Crow (or Absaroke) were originally part of the Hidatsa, a Siouan people who lived a settled, agricultural life along the Missouri River in what is now western North Dakota. The Lakota people who came to live near the 'Spirit Mound' after the Wičhíyena Sioux have a story no more than 250 years old which describes how a band of 350 warriors came near the mound late at night and were nearly wiped out by the ferocious Little People (the survivors were crippled for life). The Little People so terrified the local population, Lewis reported, that the Maha ( Omaha), Ottoes ( Otoe), and Sioux would not go near the place. The Sioux said that the devils carried sharp arrows which could strike at a very long distance, and that they killed anyone who approached their mound. Lewis wrote in his journal that the Little People were 'deavals' (devils) with very large heads, about 18 inches (46 cm) high, and very alert to any intrusions into their territory. On August 25, Meriwether Lewis, William Clark, and 10 other men traveled about 9 miles (14 km) north of the river's junction with the Missouri River to see the 'mountain of the Little People'. In 1804, the Lewis and Clark Expedition stayed for a time with a band of Wičhíyena Sioux on the Vermillion River in modern-day South Dakota. It is located within Spirit Mound Historic Prairie in South Dakota. Spirit Mound, reportedly home of some Little People.

American Elves by John E. Roth