Anastasius inherited, and promoted, religious divisions that were to cast a long shadow over the Christian Roman empire. These religious divisions derived in the first instance from the council of Chalcedon (451), which attempted to settle long-standing differences about how godhead and manhood were united in Christ. The fathers of the council were almost entirely Greek, while the pope of the day, Leo I (440–61), played an important role through his legates. A formula acceptable to the papal legates was eventually agreed, which they regarded as endorsing the teaching of Cyril, the great patriarch of Alexandria (412–44), who was held in the highest regard by all but a small minority of the eastern bishops. But as a hard-won concession to the papal legates, Chalcedon recognised the unity of Christ’s person ‘in two natures’. This is not a phrase found in Cyril, but was taken from a papal letter – the so-called ‘Tome of Leo’ – which was received by the council. This concession spoilt the achievement of Chalcedon; many Christians, especially in Syria and Egypt, felt that the council had betrayed, rather than endorsed, Cyril. Rejection of the decision of Chalcedon often took violent forms: Juvenal, bishop of Jerusalem, needed imperial troops to make a safe entry into his episcopal city; and Proterios, appointed to replace Cyril’s successor who had been deposed by the council, was murdered by the mob. The violence that often accompanied these religious differences was regularly fostered by monks, who were increasingly becoming a force to be reckoned with in the Christian empire. After unsuccessful attempts to enforce Chalcedon, in 482 Emperor Zeno (474–91) issued a statement of belief with the intention of securing unity (called the Henotikon), which disowned Chalcedon, though it fell short of condemning the council. The Henotikon was the work of Acacius, patriarch of Constantinople (471–89), and Peter Mongos ‘the Hoarse’, patriarch of Alexandria (477, 482–89). However Rome, and the Latin west in general, was not willing to disown what it regarded as the council of Pope Leo; the promulgation of the Henotikon thus provoked the Acacian schism with Constantinople, named after its patriarch, which lasted until the death of Anastasius. For the Henotikon remained imperial policy during the reign of Anastasius who, if anything regarded the edict as too moderate, since he promoted those who rejected the Henotikon for not explicitly condemning Chalcedon. Our sources for the sixth century, although on the face of it plentiful, leave much to be desired. Histories on the classical model survive intact, in contrast to the fragmentary fifth-century histories, and these include Procopius’Wars, the Histories of Agathias and Theophylact Simocatta, and substantial extracts from the History of Menander the Guardsman. These are complemented by chronicles – a new form of history writing of Christian inspiration – such as those by John Malalas (which only survives in an epitomised form) and Marcellinus, as well as the later Paschal chronicle (630) and the Chronicle of Theophanes (dating from the early ninth century, but incorporating earlier material). Church histories evolved from the form of the chronicle, and the main sixth-century example is that of the Antiochene lawyer, Evagrius Scholasticus. Such Christian history writing regarded the traditions of saints’ Lives as important, and there is a good deal of hagiographical material relating to the sixth century.Much of this is valuable for the social, as well as the religious, history of the period, notably the collections by Cyril of Scythopolis and John Moschus, together with the lives of individual saints (for example of the stylites or Theodore of Sykeon). To these can be added texts that are written, or survive, in Syriac, representing the views of those non-Chalcedonian Christians (monophysites) excluded fromthe imperial church by the drive towards a form of Chalcedonian orthodoxy promoted by Justinian and his successors. These include saints’ Lives by Zacharias of Mytilene, which were originally written in Greek, although his Church history does not advance into the sixth century; and a collection of saints’ Lives and a Church history by John of Ephesus, who wrote in Syriac.3 There is also an anonymous eighth-century chronicle, attributed to Pseudo-Dionysios of Tell-Mahre, and the twelfth-century chronicle of Michael the Syrian. Traditionally, the tendency has been to take the classicising histories at face value as a basic record, to be supplemented, with varying degrees of caution, from the chronicles and ecclesiastical sources.4 The trend of recent scholarship, however, has been to pay much more attention to the intentions and bias of the classicising historians, with the result that we now see in these sources a variety of sharply defined perspectives on the sixth century, rather than a straightforward narrative record that can be used as a basic framework.5 Archaeology is an important resource, not least over major imponderables, such as the decline (or survival) of the city, economic prosperity and climatic change. In addition we can also draw information from epigraphy, coins and seals, and make use of the evidence (still little used) that remains embedded in the conservative, yet developing, liturgy of the churches. Accounts of the second half of Anastasius’ reign indicate mounting popular unrest, ostensibly because of the emperor’s religious policy. Behind this may lie growing economic difficulties and an increasing sense of insecurity within the empire. At the beginning of the sixth century the long peace with Persia, the traditional enemy of the Roman empire, and indeed of its predecessors, came to an end. The Persians’ failure to restore Nisibis to the Roman empire, in accordance with a treaty made with Emperor Jovian in the fourth century, led the East Romans to withhold tribute payments; this, in turn, prompted the Persians to invade the Roman empire in 502 and they quickly took a number of frontier towns, including the city of Amida (see below, p. 135). To begin with, Roman resistance was weakened by a divided command, and it was not until 505 that the Romans recovered Amida. The weakness of the Mesopotamian frontier revealed by this war was remedied by the building of the fortress at Dara, close to the frontier and a few miles from Nisibis; it was called Anastasiopolis, after the emperor. In the north, too, there were threats from invaders in the early sixth century, and archaeological evidence suggests that the fortresses which Procopius says were built along the right bank of the Danube in the reign of Justinian (527–65) were at least begun by Anastasius.6 The riots venting opposition to Anastasius’ religious policywere triggered by a matter of liturgy. From the middle of the fifth century, the chant called the Trisagion (‘holy God, holy strong, holy immortal, have mercy on us’) had become a popular part of the liturgy in the east. In Syria this chant was understood to be addressed to God the Son; in order to underline the belief of those rejecting Chalcedon’s distinction between the two natures in the Incarnate Son, the phrase ‘who was crucified for us’ was added to the chant, affirming their conviction that in Christ,God himself had embraced human suffering (a doctrine called theopaschism). In Constantinople, however, the chant, with its triadic form, was understood to be addressed to the Trinity, so such an addition seemed to imply that the divine nature itself was subject to suffering. Behind the differing texts of the chant, there lay genuine mutual misunderstanding, but that only made each side’s sense of the other’s error more acute.WhenAnastasius directed that the theopaschite addition should be included in the Trisagion, it provoked a riot between non-Chalcedonian monks chanting the amplified form and the clergy and people of Constantinople. This led to popular demands for the deposition of the emperor, demands only quelled by the emperor himself facing the mob in 512, without his diadem, and inspiring an acclamation of loyalty. In the following year the emperor faced a further challenge to his authority from Vitalian, a military comes, who claimed to represent the reaction of the orthodox to the policies of the emperor. Although unsuccessful in his challenge to the throne, he outlived the emperor.