In the video below an Iraqi Christian explains that, in addition to the mostly foreign members of the Islamic State, his own Sunni neighbours told him to leave his hometown of Mosul. Ivan Watson of CNN shared similar stories told to him by Yezidi refugees. They also said they were threatened and driven from their homes by their previous neighbours who put their lot in with the Islamic State's terrorists when they conquered the area.
Christian Refugee from Mosul: Our Neighbors Drove Us Out. Source: MEMRI TV. Date Published: August 11, 2014.