“Modern violence in the Middle East is often attributed to tensions between Sunni and Shiite Muslims, an assumption bolstered by renewed fury between Saudi Arabia and Iran in recent days and fueled by rhetoric from political leaders and prominent analysts. But new data indicates bloodshed in Iraq, a central battleground for the Western war against Islamic terrorism, is caused by something altogether different.”

Source: Study: Violence in Iraq That Bolstered ISIS Not Caused Primarily by Sunni-Shiite Rift – US News