I don't want to be a downer, scully, but the first things that would turn me off about your title is beginning it "When Good Rulers Go Bad". It almost sounds like a comedy.
Just an opinion.
It's actually supposed to come across as comical. The book itself is not a comedy book. Rather, it's like those specials FOX used to air "When good animals go bad" -- the subject matter was serious but the titles were ridiculous.
So... with all the talk of imperialism and several madeup words

let me give a better explanation.
The land is ruled by one emperor at a time. I'm establishing through this, and other means, that many years ago there was a very bad, smarmy emperor. (And others throughout the history of the world) I really want to use the word Emperor in some form.
When Good Leaders Go Bad: A History of the Presidency
When Good Leaders Go Bad: A History of the Emperisy ???