In a question about leaders who rose quickly from "nothing" to supreme power, someone suggested Hitler, someone else Napoleon, then it was noticed that Hitler was a foreigner (Austrian who came into power in Germany), then it was remarked that Napoleon was Corsican (not exactly a foreigner, but anyway borderline French).
And then I notice that Stalin was Georgian, Victor Emmanuel Piedmontese, Bismarck Prussian, Getúlio Vargas a Gaúcho. All of them either "foreign" to the (most important) nation they led, or at least coming from the farthest borders of that nation.
To ask about the causes of such pattern (or whether it is a mere coincidence) would probably be deemed too broad or opinion-based to be properly answered.
So, to be objective, is there any study, book or paper, that deals with this curious set of facts?
(To notice, I am not talking about dynastic issues. True, many princes become sovereigns in foreign nations, through marriage or invitation, but that's not the issue. I am talking about actual leaders, i.e., people who won elections or revolutions or staged coup d'etats)