When I was a child (in the bygone country of USSR) and until now, I have read the same story about the word “barbarian” – the Greeks (and their Roman disciples) used the word “barbarian” for all those who did not speak their language (so, since their speech was not comprehensible, they teased the speakers by pretending they said “barbarbar”). This is taught in all schools, all over the world, but reading the original sources seems to indicate that it is just plain wrong.
First, there are the Greek sources – Herodotus, Plutarch, Polybius, Herodotus.
Herodotus goes on at great length about the Egyptians, but never calls them barbarians. Neither does he apply the term to the Phoenicians. He does apply it to the Persians and the tribes of the steppes. Same is true of Plutarch. Polybius never refers to the Carthaginians as “barbarians”.
So, why the Persians? The answer is simple: both Herodotus and Plutarch describe some rather extreme examples of despotism, and horrible tortures to whom various Persian kings and their various wives subject their, well, subjects. Now one can interpret this as propaganda (due to the ancient enmity between the Greeks and Persians), but the “control” is ShahNameh (Firdousi’s “Book of Kings”, written in the 10th/11th centuries), and that is completely in agreement with the Greek perspective – the rulers are viewed as absolute authorities (they are viewed as, essentially, gods on earth), and the heros of ShahNameh think nothing of obeying the royal orders to slaughter all inhabitants (independent of age and sex) on royal command. Indeed, Esfandyar attempts to humiliate Rostam (the greatest Persian hero) just to satisfy an obviously capricious command of King Gostashp. The wars in ShahNameh are not just – they are fought to satisfy the vanity of kings and to avenge relatively minor wrongs.
So, the conclusion is that the ancients seem to have used the term “barbarian” almost exactly the same way as we would.