My brother and I were having a conversation in regards to "The American Empire", it occurred to me that future historians might consider the borders of NATO to be the borders of "The American Empire". The romans, as far as I'm aware, had a 'friend of Rome' system, which from my understanding was a tributary system. In which a degree of self-determination is allowed in exchange for ransom, presumably (as in I'm not sure) romans could also march through their lands and even set up military installations. And if so would historians consider that country apart of Rome?

TLDR: I have a conspiracy theory that our perception of the borders of Rome are inaccurate because of a series of puppet states paid homage to Rome sort of like NATO today (minus the whole paying homage thing). How crazy am I?