The Syrian town of Baghouz, the last redoubt of the Islamic State (ISIS), was reportedly liberated on Thursday, and that means that the Islamic State’s caliphate is now definitively a thing of the past.

On June 29, 2014, the group that had up to that point called itself the Islamic State of Iraq and the Levant, or Shams in Arabic (hence the synonymous acronyms ISIL and ISIS) announced that it was forming a new caliphate – the single unified government of all the Muslims and the only government to which Muslims rightly owe allegiance, according to Sunni Muslim thought — and would henceforth drop the second half of its name and call itself simply the Islamic State.

This claim to constitute a new caliphate became the basis of its appeal to Muslims worldwide, who traveled in unprecedented numbers to Iraq, Syria and Libya to join it: it attracted 30,000 Muslims from 100 different countries.

The reason for this was the appeal of the idea of the caliphate. The caliph is the successor of Muhammad as the military, political, and spiritual leader of the Muslims. From the time of the origins of Islam until 1924, there was always a caliphate somewhere in the world. The Umayyad, Abbasid, and Ottoman caliphates were, at their peaks, massive empires. The caliph is the only person authorized, according to Sunni theology, to wage offensive jihad, and most did.

ISIS, along with al-Qaeda and other jihad groups, considered the abolition of the Ottoman caliphate by Kemal Ataturk in 1924 to be the beginning of the troubles for the Islamic world: disunity, dominance by Western powers, inability to expand the domains of Islam in any concerted manner. All of them shared, and share, the goal of restoring the caliphate. Only the Islamic State ever managed to do so, albeit only for 57 months.