This novel is set in the historical west with an eye to discuss the social ills of the time.  Life was changing as we moved from an agricultural to an industrial society.  In the west, there was an often inconvenient confluence of Native Americans, U.S. Army and industrialists.  Surprisingly, the characters are dealing with some of the same issues we do today:  cocaine, morphine, remnants of war conflicts, gunfighters, genocide and  unsavory methods to access valuable mineral rights.