NPR and the Economist have been blaming the woes of the Arab world on the Sikes Picot Agreement of 1916. Must be the centennial that brings this out. I'll grant every one of the Arab woes, but I cannot believe they have anything to do with Sikes Picot.
The Ottoman empire (forerunner to modern Turkey) used to own, operate, tax, and run all the the modern middle East, Greece and the Balkans, Egypt and North Africa. Turkish/Ottoman control began to slip in the 19th century and World War I brought Lawrence of Arabia to completely tear up the Ottoman empire. In 1916 the British and the French had Sikes (for Britain) and Picot (for France) draw up a plan to divvy up the Ottoman lands after the war. The British, the French, the Italians, and the Russians all got a big slice. Old style imperialism at work. But that's the way things worked a hundred years ago.
In reality, the local Arabs were too dis organized, too tribal, too uneducated, and too primitive to actually run things. It took 30 years for the Arabs to get up to speed and push out the European imperialists and set up their own regimes. To a certain extent, but not entirely, the boundaries of the new Arab states followed the boundaries drawn by Sikes and Picot, but so what? The populations were/are all Arab, they all speak Arabic, they are all Muslims. With the exception of Egypt, there are no natural geographic borders (mountain ranges or rivers, or deserts) so one boundary is about as good as any other.
The entire region is huge, no Arab government has the smarts, the charisma, or the military force to run the whole place. Best the Arabs can manage is to run smaller chunks of it, hence the multiplicity of regimes, Iraq, Iran, Egypt, Qatar, Syria, and so on.
So far as I am considered, the woes of the Arab lands are of their own making, it's not the fault of a diplomatic agreement among European imperialists a hundred years ago.