“They did nothing for us,” al Goud said in an interview last week in a rented house in Baghdad. “It’s all killing and disaster.”

A week later, the Islamic State executed more than 40 Albu Nimr captives on a Hit street and drove thousands of Albu Nimr civilians into the desert, where hundreds have been slaughtered – more than 400 by Monday. Tribal leaders’ calls for help from the Iraqi army and for U.S. airstrikes again went unanswered.

The Islamic State’s message to the other Anbar tribes was horrifyingly clear: Don’t fight us.