Since the Islamic State seized Mosul last summer, there has been a great deal of time spent discussing the dysfunctional nature of the Sykes-Picot border system drawn up after WW1. While there is no denying the borders did not reflect the political and social reality on the ground, the problem should not be over simplified. No matter where the borders were drawn they would have been disputed. That is not meant to minimize the mistakes made by the British and the French. Rather it means there was no simple neat way to establish a state system in the middle east even if the borders were drawn up with the best intentions. This continues to be true. There is no simple neat way to fix the mistakes of the past. Any attempt to redraw the current borders will be contested, violently in all likelihood. The states involved will object, of course, and the various political and social communities are too intertwined to be divided cleanly.
http://www.wsj.com/articles/would-new-borders-mean-less-conflict-in-the-middle-east-1428680793
IR Theory & Practice 