The Sioux meet the Lewis and Clark expedition. Post Louisana Purchase - Trading posts established throughout the West to take advantage of established trade networks.
Fur trading becomes an important part of Oglala life.
Oglala and other Lakota tribes expand their region of influence and control to cover most of the current regions known as North and South Dakota, westward to the Big Horn Mountains in Wyoming and south to the Platte River in Nebraska. 1834 - The Oglala become more centrally organized with most bands following Bull Bear with many of the rest following Smoke. This was a change from their previous more loosely governed bands with many leaders of comparable influence. The Bear Butte area in western South Dakota, extending west to Devil's Tower was the geographic and spiritual center of their world. The Oglala needed a base which provided access to the southern buffalo herds upon which their lifestyle depended.