A usual wordwide misconception is the association of the word 'Barbarian' with non-Greeks. We all know for starters Epirotes being classed as 'barbarians' from Thucydides, although they were greek-speakers. However the ultimate proof of Greek tribes being called 'barbarians is coming from Athenaios Deipnosophistes where Stratonicus the harp-player was asked "πότερα Βοιωτοί βαρβαρώτεροι...ή θετταλοί, Ηλείους έφησεν" meaning ...

  [1] Quote: It has been reported to me that it was the rhetorician Isocrates who was responsible for the servitude that the Macedonian imposed on the Persians. For the fame of the speech Panegyricus, which Isocrates delivered to the Greeks, spread to Macedonia, And it was this that first stirred Philip's animosity towards Asia. When Philip ...