An empire by definition has to include people who are not citizens of the dominant polity, otherwise it would be a nation rather than an empire. If you want to

An empire by definition has to include people who are not citizens of the dominant polity, otherwise it would be a nation rather than an empire. If you want to call the US an empire, Canada and Mexico would probably be considered part of the empire as would anywhere else that NATO or US corporations have large amounts of influence. The "barbarians"[1] would be those that actively avoid US influence like China, Russia and parts of the Middle East. [1] An unfair term, but it was also unfair when used by the Romans, so it is reasonable to use in this analogy