Oil piracy, extortion

Western and Arab officials say ISIS runs a self-sustaining economy across territory it controls in Syria and Iraq, pirating oil and extorting tribute from a population of at least eight million. The group was previously thought to depend on donations from Gulf states and the Muslim world. A farmer in Syria who has since fled the country after being forced by ISIS to pay tribute:

They demanded to be paid in gold, silver or any other precious material for the annual crop we were about to plant