The Scottish and Jewish clan/tribe systems are actually quite similar and make for a fascinating study on this subject. Often, when an outsider (English or Gentiles) invaded, only a few clans would unite to fight off the threat, while the others did virtually nothing. Clan pride was fierce and far more binding (particularly in Scotland) than any national identity, though of course the Jews had their unique religion in common as additional binding factor.

Also, how did the Macedonians and the Greeks view themselves?
Oh god.