Since 1970, the period covered by Millennium: Jahrbuch zu Kultur und Geschichte des ersten Jahrtausends n.Chr. has seen two major historiographical shifts that are distinctive to it, and it alone, namely the rise of ‘late Antiquity’ and the flowering of early Islamic studies. There is no (well-founded) disagreement about roughly when and where Islam started; but late Antiquity’s boundaries remain fluid. The Roman Empire’s painful third-century transition from Principate to Dominate amidst war against Sasanids and Germans, and the sixth century’s Justinianic consolidation of Christian East Rome, have often been attached to the core fourth and fifth centuries. A terminus c.600 is widely accepted, coinciding with Gregory the Great’s reforming papacy, and the start of the last and most dangerous war between East Rome and the Sasanids, leading to the former’s crushing defeat and the latter’s annihilation by Muslim armies emerging unforeseen from Arabia after 629. Such a cataclysm does at first sight suggest the end of an epoch, considering also the narrowing of cultural horizon it imposed on the surviving East Roman rump, and the emergence of a new empire, the caliphate. Yet, given the symbolism ancient historians attach to the Persian Wars from Marathon to Plataea (490 –79 BCE), and to Rome’s wars with its eastern neighbour starting at Carrhae (53 BCE), it is perverse to exclude the last, most dramatic of these encounters, running from 603 to 628, from the canonical narrative. Is it that adding those extra three decades would bring one so close to the Arab invasions that their Qurʾanic inspiration would become impossible to ignore, and therefore unavoidable to study? And the caliphate these wars spawned: did it not, in many respects, perpetuate the earlier empires under new management, just as its religion, Islam, responded to the earlier scriptural monotheisms, Judaism and Christianity?