It began with the Ottoman Turks. Ruling a swathe of territory from north Africa to the present Yugoslavia to the borders of Persia, and throughout the Arab peninsula, they had all kinds of ethnicity within their empire, and had worked out ways of coping with this diversity without losing control. As Empires do, they declined, with an increasingly unhealthy court culture, redolent of overfilled harems, and eunuchs with excessive power and clashes between rival princes and their mothers, while their provincial governors arrogated more and more power to themselves and distanced themselves as safely as they could from central authority.
The decline of this Empire was clear through the second half of the nineteenth century, interrupted by the emergence of outstanding talent from some of the later Emperors. The pressure on their western borders, represented first by the Hapsburgs from Lepanto onwards, grew and grew; slowly the western empire was whittled down, and gave way to what in today's world we know as Romania, Bulgaria, the constituents of the former Yugoslavia, Greece herself and Moldavia.
But our story is about the 'Middle East', or rather, the Levant.
When I read T. E. Lawrence, a noted Arabist, he described the state of the Levant beautifully. He described a chequerboard, divided from east to west, actually starting far beyond the Levant in Basra, but for the purposes of his account, from roughly where Iraq is today, to the sea-coast; again, from the north, the mountains around Anatolia, demarcating today's Turkey, down to the Sinai Peninsula in the south. Each cell was filled by a different ethnicity, and very often by a different sect; so Alawi, and Druze, and Sunni jostled each other in those narrow confines. I will not even dare to classify and list them all, being too discouraged and too pessimistic about the fate of humanity to put in further effort. Suffice it to say that as was the case in Mughal India, there was a general societal consensus, and there was generally a PaxTurcica, to use a term from modern days to those times before the First World War.
In that war, the Triple Entente, Great Britain, France and Imperial Russia, took on the Triple Allliance, Germany, Austria and, ironically, the greatest enemies of Austria, Turkey. At a fairly advanced stage of the war, the French and the British decided that they were winning, and sat down to discuss what to do with the defeated Ottoman Empire. Their thoughts turned naturally to what colonialists in those days were prone to do, to divide out the territories and swallow them up. And that, more or less, is what they did. Two diplomats, Mark Sykes and Francois Georges-Picot, (guess who represented which country?) sat down and discussed the dismemberment of the Ottoman Empire.