Originally Posted by powerclown

Good question. An overview of the political makeup of Iraq can be found HERE, among other places.

1) Northern Iraq, Kurd majority
2) Central Iraq, Sunni Arab majority
3) Southern Iraq, Shia Arab majority

The Kurds to the North are an autonomous ethnic group apart from the Sunnis & Shia. They are quite organized and relatively stable politically. Local governmental structures, based on tribal lines of authority, have been key to stability there.