Collipso said:

Now, if in that story, at the end of it the Empire is destroyed, and then a couple of years later someone decides to tell you a sequel to that story and start by saying: “once upon a time there was an empire…” again, it’ll leave you wondering: “wait a sec, wasn’t the Empire destroyed?? How did this happen???” And if the person telling the story doesn’t give you an explanation I think it’d be reasonable to think it’s some sort of plot hole in the story.