The funny thing about the Wild West thing is that it had some basis in reality (i.e. theft, raids, ranching "wars", territorial disputes, extrajudicial punishment, etc), but was romanticized into a genre through contemporary journalism and theater in the Eastern USA around the same time that it was actually happening the Western USA, basically mid 19th century to early 20th century. One pretty good book on this subject is "A Splendid Savage: The Restless Life of Frederick Russell Burnham"