You don’t seem to understand why al-Qaeda took over places like Anbar.
It wasn’t because the tribes let them in. It was because there was virtually no security in Western Iraq. And, in late 2003 early 2004 Zarqawi made a deal with the Baathists to work together. So, in comes the Baathists and al-Qaeda in Anbar while Bremer had ruled the US wouldn’t do business with the tribes and there wasn’t enough US troops to do much of anything to protect them. So they were caught between a rock and a hard place.
Some smart tribal leaders and US officers wanted in late 2003 and early 2004 to bring the tribes together to fight as one with the US against al-Qaeda. But, the CPA and Sanchez killed that plan.
Then in 2005 the tribes in Anbar decided to try to unite against al-Qaeda and Zarqawi butchered them because the US refused to help them out of fear we would be ‘giving weapons to the enemy’.
Then in late 2006 we changed our policy toward the tribes and supported them and cities like Anbar that were total warzones now have strong Iraqi police forces and Anbar is moving forward.