.
Ancient Arabian proverb: "My brother and I could fight with our cousin. Against a stranger; my brother, my cousin and I would fight together."

Sedentary Turkish proverb: "A close neighbour is preferable over a distant relative."

Arabs identified everybody who were not Arabian with a single word: عجم - ‘ajem. Gypsies identify everybody who are not Gypsie as Baro or Gaje. No need to mention Barbaros/Barbarus I suppose...
.