Al Qaeda in Iraq, ISIS's predecessor, had been defeated when the US pulled the last of its troops out of Iraq in December of 2011. The US troop "surge" that began in 2007 helped secure the gains made by an American-supported Sunni Arab uprising against AQI — the "Sahwa," or Anbar Awakening campaign that decisively shifted grassroots Sunni support away from Al Qaeda and towards the US and its partners.
But as these maps illustrate, the reach of the Sahwa by the end of the American campaign against AQI has an unnerving correspondence with the parts of Iraq now under ISIS's control...