Every time a filmmaker or showrunner takes a gamble on a big Western, a million journalists and critics start tippety-typing about how “The Western is back!” or “The Western never went away!” or “The Western is the genre we need now!” or even just—apropos of the enormous popularity of Yellowstone—“At last the ‘older’ audience gets the Western it craves and deserves!” It will be easy for those writers to apply most of those truisms, if not all of them, to Kevin Costner’s Horizon: An American Saga, an ambitious four-part epic about white people pushing into the west—and, with barely a moral qualm, taking for themselves land that had been inhabited by indigenous people for thousands of years.