So I earlier argued here that ISIS(ISIL) or DAEESH was not yet claiming itself to be a caliphate, and that its leader, Abu Bakr al-Baghdadi was only calling himself "al Hakim," or "Ruling Emir," even as I recognized that he had turned over this title to someone else, preparing the way for possibly declaring himself caliph (khalifa), while the media was already doing so inaccurately.
Well, now it has happened. Yesterday his group declared that henceforth they are to be called "The Islamic State," no more ISIS vs ISIL vs DAEESH. And his followers have sworn fealty to him as, yep, khalifa, or caliph. They are now a genuine wannabe caliphate. As usual, Juan Cole provides the best current and historical discussion at this location.
Compared to my previous piece, he has a few differences. He claims the Ummayyads were just "Arab kings" rather than caliphs, although that disagrees with most of what I have read. He claims that most Muslims accept that the caliphate died in 1258 with the Mongol conquest of Baghdad. He also claims that it was only in the 1880s that the Ottoman sultans claimed to be caliphs. Finally, he says that Taliban leader, Mullah Omar also has claimed to be caliph as well as al-Hakim, Ruling Emir, and he speculates on what would happen if he and al-Baghdadi were to end up in the same jail cell arguing over who is really the caliph. To that I have no answer, although I note that Cole also reports on details of some truly horrific behavior of al-Baghdadi prior to being thrown into Camp Bucca for 2005-2009, that he would bomb weddings and then bomb the funerals coming out of the bombed weddings. Such is our current world.
Addendum: The tale of the history of caliphates is more complicated than is presented in any of my posts or in those of Juan Cole either, with quite a few self-proclaimed caliphs running around out there in different periods, most of them with little power, and also ongoing controversies about just who was a caliph or not and how much secular versus religious power they had.
So, just to add a bit, there was another fairly serious rival caliphate to the Abbasids during 1130-1269 based in Morocco, which ruled portions of Spain for awhile as well. It may be that in the later stages of the Abbasid caliphate, there was a separation of religious from secular authority. And for the Ottoman sultans, whatever their claims earlier, it is clear that in 1880 Sultan Abdulhamid II made a major effort to assert that he was a full caliph, with this partly to make claims for ruling Muslims in India rather than the British (with some there actually recognizing his authority), as well as offsetting modernizing/Europeanizing "Young Turks," who would in the end overthrow both the sultanate and the caliphate in 1924 when Mustafa Ataturk was i power.
And for those of you for whom it matters, Ramadan Karim, really (and apparently the now "IS" chose the first day of Ramadan to make their announcement, for better or worse).