Da'esh has, for much of its reign of terror, been funded from a range of sources. Although it is difficult to say exactly, the general feeling is that the largest, or close to the largest, has been from the sale, albeit on the black market, of oil. After a period in the doldrums, oil prices are rising again and, therefore, so will Da'esh's funding. But, of course, it's more complicated than that.
