Native American cultures were already firmly established on this continent several millennia before the time the first European and Asian explorers discovered the East and West coasts of the America.  The first recorded ventures exploring West of the Mississippi River were the hordes of trappers and traders who came like a wind after the Lewis and Clark Expedition.  They first came looking for the fortunes to be made in the fur trade.  Besides the British owned Hudson Bay Company, there were domestically sponsored companies such as the American Fur Company.  Moving freely among these large operations were a army of free trappers.  The result was an exhaustive exploration of the territories by the British and Americans for the respective governments and a showdown over who would, in the end, gain the land and it's bounty.  The British thought that if they trapped out all the beaver, the Americans would soon lose interest in the land.

The Americans had other plans - and won the battle.