Aristotle was Macedonian. He attended Plato's Academy in Athens for about twenty years. He returned to Macedonia for a while, in part to tutor a young Alexander the Great, and then went back to Athens to found his own school, the Lycaeum. Though he spent most of his life and career in Athens, he was never an Athenian citizen, but more of a resident alien, with few political rights (he could not own property, for instance). Indeed, throughout his life, he was never a fully-fledged citizen of any Greek polis.
Citizenship in Greek city-states was usually limited to a minority of adult males. It included more responsibilities than the more passive matter-of-fact citizenship that is typical today. And it usually assumed that those who were citizens shared common goals, a common outlook, and a mutual interest in the success of the polis.
Greece was divided politically into territories ruled by many independent city-states. These often formed alliances and sometimes centrally-governed confederations (particularly in times of war). Some developed colonies, both as ways of finding new agricultural land and as ways of giving a restive underclass something to do at some distance from the ruling class.
There is a reference in the Politics to the assassination of Philip II of Macedon, which happened in 336 BC. So we know that at least some of the work was composed after the expansion of the Macedonian kingdom under Philip II which resulted in its dominion over Athens and much of the rest of Greece, subordinating Greece's many city-states to a foreign empire.
As a Macedonian and tutor to Alexander the Great, Aristotle was well-placed to be in the good graces of the political leadership of his time, until Athens challenged Macedonian power towards the end of Aristotle's life, and he went into exile from Athens to avoid the possibility of being attacked by anti-Macedonian Athenians.
