Didn't Ionian and Dorian Greeks speak two different languages? And weren't there Ionian cities where Dorians were not allowed to set foot? I guess my question

Didn't Ionian and Dorian Greeks speak two different languages? And weren't there Ionian cities where Dorians were not allowed to set foot? I guess my question is, how can primitive peoples bring such total destruction over such a large area? Rome barely manged to wipe out Carthage and it wasn't easy. Completely exterminating people isn't easy.