Perhaps ISIS did not exist as a separate entity when Dubya was President, but the Muslim Brotherhood and the Wahhabi mission did. As al-Qaeda was taking a beating in the public marketplace of the world, an alternate was being quietly funded and trained up, using the lessons learned, and the technical savvy gained was employed to create the new franchise, known variously as Islamic State, ISIS, ISIL or by the transliterated Arabic acronym DAESH.
There are those who would argue that this entity is not “Islamic”, but to the contrary, it is the very PUREST form of Islam, back to the very fundamentals as practiced by Mohammed Ali himself.
Both Wahhabism and the Muslim Brotherhood are traced back to the rise of the vast wealth of the Saudi kingdom and a desire to “restore” the One True Path (and kick the butts of the Shi’a thoroughly and for all time).