outpost built following the Louisiana Purchase..." http://www.epsi.net/graphic/osage.html Fort Osage - later "known as Fort Clark or Fort Sibley - was part of the United States factory trading post system for the Osage Nation in the early 19th century near Sibley, Missouri ." http://en.wikipedia.org/wiki/Fort_Osage Historic Fort Osage http://www.fortosagenhs.com/ Kansas Forts of the