Wyoming's history is one of the native peoples who inhabited the region—the Cheyenne, Sioux, Crow and Shoshone tribes, to name a few—and an emigrant frontier. In the 1840s and 50s, nearly half a million pioneers, gold rush Forty-Niners and Pony Express Riders embarked along the Oregon Trail during the greatest overland migration the country has even seen. Risking their lives, they traveled across the continental divide to settle the western wilderness in the name of Manifest Destiny. Historical sites such as forts, trading posts, and old western towns still line the original trails and remain as reminders of the rugged frontier life. The Wind River Indian Reservation and its people are an important part of the culture and economy of Wyoming.