The spectacular Roman triumphs over the Parthians during the second century were a vivid testament to the power of Roman arms, but they had been won against something of a paper tiger. The Arsacid dynasty was weakening. During the reign of Septimius Severus, a revolt against the Parthian throne had begun under a man named Pabag, whose son, Ardashir, would emerge as the first of the ‘Sasanian’ kings of Persia (224–42). Pabag was a priest of the Zoroastrian cult of Anahita at Istakhr, the capital of Fars (Persis), one of the most important of the Parthian satrapies and the old heartland of the Achaemenid Persian empire. The conjoining of the political and the religious in the revolt was highly significant, because the political identity of the Sasanian empire would be largely shaped by the close ties between the new kings and the Zoroastrian priesthood. 1 By 224, Fars had come under Sasanian control, and in the same year, Ardashir defeated and killed the Parthian king Ardawan (Artabanus) at Hormozgan. Meanwhile, Septimius Severus had died while on campaign in England in 211, and while in theory the throne passed equally to his sons, strife between the violent and bloodthirsty Caracalla (who imagined himself as a latter day Alexander the Great) and the more mild-mannered Geta resulted in the latter’s brutal murder before the year was out. 2 Caracalla then launched an expedition against the Parthians, honouring Achilles at Troy on the way before allowing Roman troops to plunder the Parthian royal tombs at Arbela (Erbil in Kurdistan). 3 Caracalla was murdered shortly afterwards as he dismounted from his horse to relieve himself. 4 Following the brief reigns of Macrinus and the eccentric Elegabulus, the Roman throne passed to Alexander Severus, whose murder in the spring of 235 during an army mutiny at Moguntiacum (Mainz) would mark the end of the Severan dynasty, and the beginning of a tumultuous period in Roman history commonly known as the ‘Third Century Crisis’. 5