Which would include all those Baathist tribes.
The authors also emphasise that IS is not new, but rather emerged from the ashes of Al-Qaeda in Iraq (AQI), one of the most brutal foes of the Americans following their 2003 invasion. AQI was largely defeated after the US convinced local tribes to rise up against them -- a strategy known as "The Awakening", which has deeply influenced IS strategy.
"From the beginning, they've been obsessed with the Awakening," said Hassan. "They've done everything to prevent it happening again: built sleeper cells, bought loyalty, divided communities. "They've succeeded in making internal resistance practically impossible. No tribe will fight them, because they will find themselves fighting their own brothers and cousins.".....snip~
IS has built near-impregnable base and mass appeal: new book