What are the critics that define a barbarian for the Greek and Roman world? Please help me, I've been working on it for several days. Thanks in advance

The people who defined what a Barbarian was in the Ancient Greek and Roman world were the Roman and Greek intellectuals, who each considered their own culture to be most superior culture in the world at the time, and who looked down on other cultures.

Explanation:

People like Pythagoras, Plato, Aristotle (Greeks), or Seneca, Cicero, and Tacitus (Romans) deemed to be "Barbarians" all those peoples who did not belong to either Greek or Roman civilization, and they wrote books that supported these views. The common people simply took these views at face value and did not reflect too much on them, since most people at the time were illiterate in first place.

the church governed the society after the empire fell.   constantine took charge of rome and ended the confusion which had over religion and made christianity as the only religion and that started ruling the roman empire. he also divided the empire into two and fortified the eastern part.   he ruled the eastern part.