The Illyrian emperors (Latin: Illyriciani) were a group of Roman emperors during the Crisis of the Third Century who were of Illyrian origin and hailed from the region of Illyria (Latin: Illyricum, in the Western Balkans), and were raised chiefly from the ranks of the Roman army (whence they are ranked among the so-called "barracks emperors"). In the empire the Illyrian generals had established a powerful military caste.
In the 2nd and 3rd centuries, the Illyricum, which included the provinces on the Lower Danube (Dacia, Raetia, Pannonia, Moesia), held the largest concentration of Roman forces (12 legions, up to a third of the total army), and were a major recruiting ground. The advance of these low-born provincials was facilitated by a major shift in imperial policy from the time of Gallienus (253–268) on, when higher military appointments ceased to be exclusively filled by senators. Instead, professional soldiers of humble origin who had risen through the ranks to the post of primus pilus (which also entailed admission to the equestrian order) were placed as heads of the legions and filled the army's command structure.
