Last night, when the U.S. began walloping ISIS militants in Syria, our jets also hit the Khorasan group, hardcore Al-Qaeda veterans who are reportedly expert bomb-makers. When I first heard the news on the radio in my car, I wondered why Al-Qaeda had a group called “Corazón”—some Spanish-speaking faction, perhaps?—but then I realized I’d already written about the original Khurasanis. They were the muscle behind the Abbasids: the third Islamic caliphate, the dynasty associated with Baghdad’s founding and golden age, and the contemporaries of the Carolingians.

The fourth chapter of Becoming Charlemagne takes readers on a tour of Baghdad around the year 798:

In the ritzy Harbiya suburb of northwest Baghdad, the families of soldiers started each day with expectant prayers. In summer, they awoke in their cool basement apartments, or on their rooftops within sight of the Round City, where they greeted the dome at the hub of their city.

As a boy, the current caliph, Harun, had led their fathers and husbands to the frontiers against the Rum, the so-called Romans of Constantinople, the ones whom poets called al-asfar, “the yellow ones.” More recently, they had been paid to quash local rebellions, commanding armies in the service of the caliph. In a caliphate that stretched from northern Africa to India, there was a constant market for well-armed men. Praised by their contemporaries in story and song, these generals rarely lacked for work.

The comfortable estates of Harbiya had been built on that same military might. Only a few generations earlier, these soldiers had stormed out of the eastern province of Khurasan, bringing to power the descendants of al-Abbas, the uncle of the Prophet Muhammad, in a show of force and a flurry of black banners. The Abbasid caliphs had rewarded the Khurasanis with desirable land and jobs for their children, who now commanded the palace guard and ran the police force.

As this blog has long shown, Europeans and Americans love to dress up in medieval costumes, follow pseudo-medieval soap operas on television, construct medieval-ish buildings, and otherwise evoke or re-create the Middle Ages, sometimes to spurn the modern world, more often to carve out a place in it, whether individually or in groups. With their choice of name, the Khorasan nutjobs are heeding that same inexhaustible impulse. I can respond only by marching out one of my favorite observations from scholar Tom Shippey: “There are . . . many medievalisms in the world, and some of them are as safe as William Morris wallpaper: but not all of them.”