It's the continuation of a very old quarrel. For example: Around 250 BC that general area of the world (the Middle East) was being fought over by the people of Pontus (more or less where central Turkey is now, and probably the progenitors of today's Turkish nation), the Armenians (to the East), the Parthians (a little farther southeast), the Seleuceids (Greeks, part of Alexander's old empire), the Egyptians, various smaller tribal groups, and some other Greeks around Halicarnassus and what is presently the western end of Turkey along the Mediterranean coast.

They all hated each other with a passion. They constantly conspired against each other. They invaded and slaughtered each other whenever they felt strong enough to do so. They made temporary alliances to gain an advantage, then stabbed their allies in the back when the opportunity arose. The Romans finally came and conquered all of them. Later the Romans had to leave, and the whole mess started up again, and has continued to this day, although the names have mostly changed.

Things are actually a bit better now. It's no longer considered morally acceptable to burn down other people's cities, slaughter most of the inhabitants, and enslave the survivors.

Be thankful for small mercies, I guess.