How is that a prequel? It was made after Fistfull of Dollars and For a Few Dollars more, and was focused on a Civil War campaign that actually happened. (No it was not a documentary).
Not seeing it as a prequel. It was a stand alone good film
Not a prequel.
OK Rogue One was a good prequel. Not as good as original, but good.Rogue One and Red Dragon were good.