 Complete the following phrase:  In the early 19th century, when the Euro-Americans first entered the area, the area was inhabited by Comanche, Shoshoni, and Ute tribal groups. Blackfoot, Sioux, Cheyenne, Arapaho, and Navajo tribes also visited or used the area. The use of the area by Native Americans was documented by the 1776 DomínguezEscalante expedition and by the 1805 Lewis and Clark Expedition. In the 1830s the valley became a favorite location for fur trappers and settlers. In 1837 Fort Davy Crockett was constructed as a trading post and as defense against attacks by the Blackfoot. The fort was abandoned in the 1840s and the population of settlers declined. After the 