The Near East before the coming of Islam was dominated, as it had been for the previous half-millennium, by two great empires, the Roman–Byzantine to the west and the Persian to the east. The frontier between these two empires had fluctuated considerably during this time. In the late sixth century, the last period of stability before the upheavals of the seventh century, the frontier had run roughly from north to south, through the wild uplands of eastern Anatolia and bisecting the fertile and well-populated plains of the land between the middle Tigris and Euphrates rivers, the prairie and steppe country which the Byzantines called Mesopotamia and the Arabs were to know as al-Jazīra, “the Island” between the two great rivers. On the Byzantine side of the frontier lay the massively fortified towns of Amida (now Diyarbakır) and Dara, while the Persians held the ancient cultural centre of Nisibis (Niṣībīn). On the Euphrates, the frontier zone was marked by the sixth-century Byzantine fortress of Zenobia. It was in this zone of the frontier that campaigns between the armies of the two empires took place; the heavy, slow-moving forces could not hope to cross the waterless stretches of the Syrian Desert to the south.

South of the Euphrates, there was no firm frontier. During the second half of the sixth century, both Byzantines and Sasanians had reached arrangements with leading clans among the Arab bedouin tribes, the Ghassanids and the Lakhmids, respectively, who provided an element of administration in the frontier areas as well as defence against their opposite numbers on the other side of the desert. This reliance on pastoral peoples for the defence of the empires testifies to their growing importance along the desert margins and the inability of the settled people to provide their own defence.

In the year 600, the Byzantine Empire presented a superficial picture of ageless continuity. The emperor of the day, Maurice, bore the title of Augustus and claimed to be the successor of that first Augustus who had established his personal power in Rome over 600 years before. It is true that the capital had since moved to Constantinople and that Christianity had become the official religion of the empire, but the emperor still ruled with the assistance of the senate, consuls were still appointed, the laws of the empire were based on Justinian’s great codification of classical practice and Latin was still used as an official language, although it was increasingly being replaced by Greek for administrative purposes.

This impression of continuity, however, masked a large number of changes, and the Roman Empire was continually evolving in response to fluid circumstances. Many of the features which had seemed central to the classical empire were no longer in evidence. Until the fourth and fifth centuries, the eastern half of the empire had at least in theory boasted a large number of self-governing towns which managed their own affairs under their own councils and collected taxes from the surrounding countryside. This urban government had brought great prosperity to some cities and resulted in a burst of civic architectural activity which can have had few parallels and which created the great monumental baths, theatres and colonnaded streets whose ruins remain so impressive today. By the sixth century, this picture had substantially changed; the cities had lost their political and financial autonomy; their councils had been superseded by governors appointed by the imperial authorities and their civic revenues had been confiscated for the benefit of the imperial treasury. While churches and monastic buildings continued to be constructed, large-scale civic building effectively came to a halt.

The sixth century saw further blows to the urban culture of late antiquity. In 541, bubonic plague struck the eastern empire for the first but by no means the last time; it was to recur with a horrifying frequency throughout the sixth and early seventh centuries. Mortality is impossible to gauge with any accuracy, but using contemporary accounts and comparing them with the much better documented Black Death of 1348 onwards, it seems probable that at least a third of the population was lost. Furthermore, it is likely that the highest mortality was in densely populated urban areas, while the nomad populations were comparatively unaffected. There certainly seems no evidence that the plague spread into the Arabian Peninsula. This massive loss of population was compounded by a further series of disasters, both natural and man-made. The mid-sixth century saw a number of devastating earthquakes which effectively destroyed Beirut, until then a flourishing intellectual and legal centre, and other cities on the Lebanese coast. At the same time, the Persians launched a series of very destructive invasions of the Syrian provinces, including the sack of the great city of Antioch in 540 and of Apamea in 573. In 582, the major provincial capital of Bostra (now Buṣrā) in the Ḥawrān was sacked by the followers of the Ghassanids, protesting the arrest of their chief by the Byzantine authorities. These incursions were paralleled elsewhere; in Italy, most of the lands which Justinian had painstakingly retaken from the Visigoths were lost to the empire when the Lombards invaded from the north in the second half of the sixth century. Nearer the capital, the Balkan provinces were devastated by the attacks and settlements of Avars and Slavs.

These catastrophes had a fundamental effect on the Byzantine Empire. Most obviously, it was weakened militarily – the loss of population and the constant wars reduced the army greatly; the system of limitanei, frontier guards who performed military service in exchange for land, was largely abandoned, and it seems that by the early seventh century, imperial armies were increasingly composed of people from the fringes of the empire, Armenians and Arabs, rather than the settled inhabitants of the central areas. In addition, the empire was becoming a rural and agrarian society, not just in Italy and the Balkans, but also in the Near East, where urban life was slightly more resilient. There was still Mediterranean trade until the end of the sixth century, notably in grain from Egypt and in pottery, but the cities of the Syrian and Palestinian coasts seem to have lost much of their commercial vitality. In so far as trade was carried on, it was likely to be centred on fairs attached to pilgrimage centres rather than on large urban markets, and it is possible that monasteries and churches had replaced urban notables as the most important landowners. Nor were there any traces left of local self-government. For both administration and defence, the people of the Byzantine Near East were dependent on imperial armies and officials. By the end of the sixth century, the Byzantine Near East had effectively lost its classical aspect and was going through a series of profound economic and social changes not dissimilar to those which occurred in western Europe at the same time. It is against this background that the achievements of the Islamic conquest and Muslim state-building must be measured.

In addition to these general changes, Syria and Egypt had a number of problems which made them rather different from the rest of the empire. The first was one of language and ethnic identities. Both countries were essentially lands of two cultures, the one urban, Greek-speaking and influenced by classical cultural norms and lifestyles. This culture was at its strongest in the great urban centres like Antioch and Alexandria, but also thrived in many lesser coastal and inland towns. The other culture was vernacular, Coptic in Egypt, Aramaic or, increasingly, Arabic-speaking in Syria. This was the culture of the villages and the pastoral peoples, who had no access to the traditions of the classical world and little taste for the amenities of urban life. For almost a millennium, since the conquests of Alexander the Great, these two lifestyles had coexisted in mutual incomprehension. Now, with the relative decline of urban populations and prosperity, the vernacular world was in the ascendant.

These cultural differences were reflected in religious ones. During the sixth century, the bulk of the rural populations of Egypt and Syria (but not, it would seem, of Palestine) became attached to the Monophysite, also known as Miaphysite, faith, in distinction to the official, imperial, Diophysite view. The differences between these two views concerned the nature of Christ. The Diophysites maintained that He had two complete natures, one human, like our humanity, and one divine, miraculously fused in one person. The Monophysites refused to accept this, holding that Christ had one, divine, nature, that His humanity was not as ours, to them a blasphemous idea, but only an aspect of His divine nature. Superficially, the differences may seem to be trivial, but in fact they show a fundamentally different way of looking at the Incarnation, and they stem from different religious traditions: the Diophysite looks back to the Hellenistic tradition of humanizing the divine, whereas the Monophysite looks to aspects of the Jewish tradition with its deep distrust of any representations of divinity.

The differences of theological opinion would probably have remained talking points among theologians if they had not reflected the broader cultural distinctions. The Monophysite church used vernacular languages for liturgy, theological debate and general literature – Syriac (a literary form of the Aramaic dialect of Edessa) in Syria and Coptic in Egypt; both of these languages, incidentally, remain in use as liturgical languages to the present day. The Monophysite church, too, was essentially rural, at least in Syria, where its leaders, although they took the ancient title of patriarch of Antioch, always lived in monasteries far from the city itself. The differences were greatly exacerbated by the fact that the Byzantine authorities, in a struggle to enforce ideological uniformity, began the systematic and often brutal persecution of the Monophysite church, especially in Syria. The Monophysite church had, however, powerful lay supporters in Syria, notably the Ghassanids who controlled the desert frontier and provided both money and refuge for persecuted members of the sect when they were forced to flee from the centres of population. The significance of this for the longer-term history of the Near East was that it meant that a significant proportion of the population was alienated from the ruling class both culturally and because the church they were devoted to was regarded as heretical and subject to dire official sanctions. It is important, at the same time, not to overestimate the significance of this: there is no evidence that either the Copts or the Monophysites of Syria actually cooperated with the Islamic conquests. What can be said is that they felt little enthusiasm for the Byzantine cause. In some parts of Syria, the conquerors were actually welcomed; in no part was there significant and prolonged resistance from the local population, as there was, for example, in the Anatolian highlands, Armenia or the province of Fārs in southern Iran.

The long-term weaknesses of the Byzantine Empire in the Near East were revealed in the series of catastrophes which followed the death of the Emperor Maurice in 602. Maurice, a capable and energetic soldier, if a slightly ham-fisted politician, had devoted his reign to the maintenance of the frontiers of the empire. In doing so, he had been greatly aided by a long-term alliance with the Persian King Khusrau II Parvēz, whom he had previously helped to the throne. This breathing space in the east had allowed Maurice to devote his attentions to securing the frontiers of the state in the Balkans. In 602, he was murdered, along with all his family, by a brutal and incompetent usurper called Phocas. Not only did Phocas prove totally unable to continue his predecessor’s work in the Balkans, but his action gave Khusrau II the pretext to launch a major invasion of the Byzantine Empire to avenge his dead benefactor. The effect was catastrophic: the Persians penetrated much farther than ever before; not only were Antioch (613) and Jerusalem (614) taken, and with them all the provinces of Syria and Palestine, but so was Egypt, and much of the Anatolian uplands were devastated by raids; recently discovered archaeological evidence testifies to the extent of destruction of Anatolian cities at this time. Meanwhile, in 610, Phocas was himself deposed, by a soldier from the Byzantine territories in north Africa, Heraclius. Heraclius was altogether more effective than his predecessor. In 622, the same year that Muḥammad made his Hijra from Mecca to Medina, he set off from the beleaguered capital at Constantinople and led an expedition through the Black Sea to take the Persians from the rear. In a series of brilliant campaigns, he destroyed the Persian army and marched into the heartlands of the Sasanian Empire in Iraq. Khusrau was deposed, and in 628 (the year Muḥammad reached agreement with the people of Mecca), Heraclius entered the Sasanian capital at Ctesiphon. The Persian conquests in Syria and Egypt were restored to Byzantine control and the relic of the True Cross, taken by Khusrau, was restored to Jerusalem.

The appearance of a return to normality was deceptive. The long years of warfare had accelerated and confirmed the tendencies of the previous century towards demographic and urban decline. Many previously settled areas on the fringes of the Syrian Desert were now deserted, their inhabitants being dead, in exile or converted to pastoral lifestyles more easy to sustain in the chaotic conditions. Furthermore, a whole generation had grown up which had no memory or experience of Byzantine rule: those who were adults at the time of Heraclius’ triumphs had been children when the wars began, and they can have had little residual loyalty to the Byzantine state. Heraclius was faced with a multitude of problems, none of which he had time to solve. The military and administrative organization of the recovered provinces had been hardly developed and, apart from Arab tribesmen, taken on as allies, there was no chance to develop the sort of local defence unit, the theme, which was to prove so effective in Anatolia. City walls and fortifications were probably in drastic need of repair. The emperor also failed to resolve the religious issue. In Syria, he attempted to reach a compromise between Diophysite and Monophysite views, putting forward a formula known as Monotheletism. This was to form the intellectual basis of Maronite Christianity, and as such still survives to this day, but at the time it served to please no one, least of all the wild and truculent monks who led the Monophysite party. In Egypt, he was unwise enough to appoint, as both patriarch and governor of Alexandria, a militant Diophysite, Cyrus, bishop of Phasis, in the Caucasus (hence his Arabic name, al-Muqawqis). Cyrus proved to be both incompetent and intolerant, and the restoration of Byzantine rule in Egypt was marked not by the restoration of Christian unity but by the systematic alienation of the majority of the population from the government. If Heraclius and his successors had been able to enjoy the fruits of their triumph for a few decades, it is possible that a new structure would have emerged in the Byzantine Near East. But this was not to be; the Islamic armies arrived when Byzantine rule was recent, shaky and widely resented. The Islamic conquest of Syria and Egypt was as much a product of the decline of Byzantine civilization in the area as the blow which destroyed it.

The Sasanian Empire of Persia of the late sixth century was, like the Roman–Byzantine Empire, heir to an ancient imperial tradition. The great Achaemenid Empire of Cyrus, Darius and Xerxes had flourished when Rome was a village, and the Sasanian family were well aware of the fact that the Persian Empire had existed since remotest antiquity. The ruling family had come to power over 300 years before; the first member of the dynasty, Ardashīr Pāpagān, was the sub-king of Fārs, the area of southern Iran which had been the cradle and centre of the Achaemenid dynasty. Even though Achaemenid power had vanished 600 years previously when Alexander the Great took and burned Persepolis, Ardashīr chose to have his achievements commemorated among the great monuments of that vanished supremacy.

Unlike the Byzantine Empire, power in the Sasanian Empire was essentially dynastic. In Byzantium, it was possible for a family, like that of Constantine in the fourth century, to establish control of the empire for several generations, but a dynastic ideology never developed. In Iran, however, by the sixth century, the Sasanian house was held to have a divinely given right to the throne, and when, from the late sixth century, generals of non-dynastic origins challenged and usurped this right, they could not command the necessary prestige to hold the empire together. In Byzantium, a successful usurper like Heraclius could be, and was, accepted as legitimate sovereign. In the Sasanian Empire, rebels like Bahrām Chōbīn (590–591) and Shahrbarāz in 628, although both were of aristocratic descent and proven military ability, failed to win general acceptance because they were not of the ruling dynasty. In the crisis conditions which prevailed in the empire after the deposition and death of Khusrau II Parvēz in 628, this weakness made it difficult for an effective sovereign to emerge; in the years 628–632, there were at least ten different kings or would-be kings, and by the time that Yazdgard III, a scion of the Sasanian house who had been discovered hiding in the ancient capital of Iṣṭakhr in Fārs, had been established on the throne, the Muslim armies were already attacking the empire.

There were other ways in which the Sasanian imperial style differed from the Byzantine. Both claimed to rule by divine pleasure, and the Sasanian sovereigns claimed the support of Ahurā Mazdā, the Good God. But they also claimed divinity for themselves, and the ancient Near Eastern idea of the God-King remained very much part of the imperial ideology. With it went a vastly elaborate court ceremonial, a hierarchy of offices at least as formal as anything devised in Constantinople and a concern to distance the sovereign from even the greatest of his subjects. There was also a different imperial iconography: the Byzantine emperor, like Justinian in the Ravenna mosaics, tends to appear as a formal, distant, immobile figure, almost always in civilian dress. Khusrau II Parvēz, in the rock reliefs he caused to be carved at Ṭāq-i Bustān, had himself portrayed as a mighty hunter, on horseback in pursuit of game; it was an imperial image which dated back to the Assyrian monarchy of the first half of the first millennium BC. In a real sense, the Sasanian was the last of the great monarchies of the ancient Near East.

At the end of the sixth century, the Persian Empire controlled virtually the whole of the Iranian plateau and all of modern Iraq. On the west, its frontiers coincided with the edge of the settled lands, and the Sasanian clients and allies, the Banū Lakhm of Ḥīra, extended this influence over a confederation of bedouin tribes. To the north, the Persians held Nisibis (Niṣībīn) and their influence was preponderant in Armenia. Under Khusrau I Anūshirvān (531–579), the northern frontier had been established in the Araxes valley, at Tblisi in Georgia and at Darband, the great fortress on the Caspian coast which controlled the eastern flanks of the Caucasus; in this area, the Muslims inherited Sasanian political geography, manning the same frontier fortresses and settling in the same cities as their Persian predecessors. The northeastern frontier was always disturbed and far from the heartlands of Iranian power. The lands of the Oxus valley and beyond had been invaded from the fourth century by Hunnic people known as the Hepthalites. In around 560, Khusrau I, in alliance with the Turkish nomads who also inhabited the region, defeated the Hepthalites and their kingdom was broken up. From this time, the Sasanian frontier was established at Marv, where a frontier official called the marzbān was established. Recent archaeological research has revealed remains of the great Gurgan Wall, a well-planned military installation with regular forts along it, which demonstrates the power and efficiency of the Sasanian military machine and rivals any of the systems of fortifications constructed by the Romans. Beyond that, various independent principalities were ruled by Hepthalites or Soghdians, largely settled people of Iranian origin. The steppe lands and deserts of this area were the province of the Turks, pagan, horse-based nomads whose domain stretched as far as the borders of China and who were destined to play an immensely important part in Islamic history. In the southeastern direction, the frontiers of the empire seem to have coincided roughly with those of the eastern frontiers of modern Iran, including Sīstān, where there was a marzbān at the capital Zaranj when the Arabs arrived, and Kirmān.

In the sixth century, Sasanian influence was not confined to Iran and Iraq. Some areas of the Arabian Peninsula, notably Baḥrayn and al-Yamāma and from 572 Yemen in the southwest, were also controlled by the Sasanians or their allies and they encouraged a trade in the Gulf which was to continue after the Muslim conquest.

Despite the impression of great antiquity and the appeals to a great imperial past, the Sasanian Empire, like the Byzantine, was by no means static; during the sixth century, it had gone through remarkable and deep-rooted changes. The history of the Sasanian monarchy can be interpreted as one of constant tensions between the attempts of the dynasty to establish a centralized authority and the determination of the higher aristocracy and local kinglets to maintain their rights and independence. The Parthian monarchy, which had preceded the Sasanians, had been little more than a confederation of minor kingdoms. The early Sasanian monarchs tried to create a more centralized regime, but during the fifth century, this process was largely reversed and there was...