Many of the modern day problems in the Middle East stem directly from us and France drawing random lines across the territory to divide it up post-WW1. But even if we'd just walked away and left them to their own devices the national, tribal and religious rivalries would have ensured the place was in a continual state of upheaval.
Take 1948, when Israel declared statehood and was promptly attacked by Egypt, Jordan and Syria (among others). Egypt & Syria were rivals, not allies. Both saw themselves as leaders of the Arab world and therefore having the right to the territory. Syria saw the new state of Israel (& Jordan) as natural parts of a greater Syria. Egypt wanted the territory as a buffer against Syrian expansionism. Jordan wanted Egyptian control of the southern part of Israel to give them a direct link with Egypt, giving them some safety against Syria.
It was only the prospect of the UK military leaving the Gulf Area under the Wilson Government that forced the UAE states to stop fighting and combine to form a federal state. Otherwise they'd probably have been eaten up by the likes of Saudi Arabia.
