I've noticed this trend where almost all the top brass of IS is/was from either al-Anbar or Nineveh(specifically Tal-Afar), especially the former. The biggest exception was al-Baghdadi who was from Samarra but other than that, I struggled to find any who were from elsewhere.

I know that Anbar was the most rebellious province towards the occupation but where are all the leaders from Baghdad or Diyala? They suffered the most under sectarian violence which would make them perfect candidates for an organization which is first and foremost a sectarian one.