Cultural divisions were reinforced and defined by religion; Christianity in Byzantium and western Europe from northern Iberia to the Elbe, Ireland to the Hungarian plain; Islam to the east and south, in western Asia, north Africa and the southern Mediterranean. Neither religious block was united. In the later tenth century, the traditional authority of the caliph of Baghdad had been usurped in Egypt by a caliph adhering to the minority Shi’ite Islamic tradition that had separated from the majority, orthodox Sunni tradition in the late seventh century over the spiritual legitimacy of the successors of the Prophet. In Spain, the Muslim community owed allegiance to an indigenous caliphate, based at Cordoba, until its disintegration and fragmentation in the early eleventh century. In Christian territories, although a sharper separation of powers existed between religious and secular authority than in Islamic states, two main distinctive forms of Christianity had developed since the later Roman empire; the Greek Orthodox tradition based on the Byzantine empire and a Latin tradition theoretically centred on the papacy in Rome but largely driven by the twin forces of local, aristocracy-led churches and a network of monasteries. In both Christianity and Islam, apparently monolithic belief systems concealed within them infinite local variety and tensions born of social, linguistic, ethnic, cultural and geographic diversity and distance. There were few non-Christians in lands ruled by Christians, although Jewish communities were spreading from the tenth century north of the Alps, especially to France and the Rhineland. By contrast, every Muslim region contained non-Muslim inhabitants, often in large numbers, mainly those Islamic law called the People of the Book, Jews and Christians, the latter from a range of local sects and confessional traditions deriving from late Roman theological interpretations different from either Latin or Greek orthodoxies.
In central areas of this Afro-Eurasian region, those of Christian and Muslim observance and rule, the religious and political structures rested on settled agrarian economies and populations. Byzantium and the Islamic states shared a flourishing commercial system that supported gold currencies and towns, while in Christian western Europe, by 1000 urbanization – or, in the perspective of the Roman empire, reurbanization – had only recently begun to accelerate along the major trade routes north of the Alps: the North Sea and north-west Mediterranean coasts, the Rhine, Rhône, Seine, Loire, Thames. In Italy towns and cities had survived more robustly since the collapse of the late Roman economy and civilization, even if on a far smaller scale than further east. The economic imbalance was reflected in the size of cities in the eleventh century. In the eastern Mediterranean, the great metropolis cities boasted populations of hundreds of thousands – Baghdad perhaps half a million; Old Cairo slightly less; Constantinople perhaps 600,000 at most. In Muslim Spain, 100,000 people may have lived in Cordoba, although some estimates make it much more. By contrast, the largest western Christian cities – Rome, Venice, Florence, Milan, Cologne – hovered around 30–40,000. Paris and London in 1100, sustained by a largely rural hinterland, probably counted about 20,000 each, the equivalent of rather third-rate cities in the Near East or less. Elsewhere in northern Europe, cities were even smaller, while some important towns could muster only a very few thousand inhabitants. One of the striking features of the following two centuries lay in the massive growth in western urban populations, but even by 1300 cities such as Paris, pushing towards 100,000, still barely competed with the great entrepôts of the eastern Mediterranean.
Even with heightened economic and commercial activity in western Europe, the imbalance of trade remained evident, the west having to rely on an often limited silver coinage as the wealth flowed eastward and southward, gold, much of it from west Africa, never reaching or staying in large enough quantities to sustain currencies beyond the Pyrenees, Alps or Danube. International trade revolved around luxury items, notably spices and finished textiles such as silk from the east and slaves, fur, timber and some metals from the west and north. Local exchange, primarily of foodstuffs but also certain basic living materials, such as wool and woollen cloth, provided the main engine of regional commerce in the rural economies. The mosaic of local economies varied widely across the region: cereals, wheat in the more southerly areas, rye and oats further north; wine in the south, beer in the north; sugar cane in Syria; olives around the Mediterranean; fishing everywhere along the enormously long shores of Afro-Eurasia. The growth of towns in Europe between the Alps and the Atlantic indicated an acceleration in such commercialization, a process that acted as a liberating dimension for large sections of the peasant communities who were mainly tied to the land by law, hierarchy, custom, coercion and economic necessity. In market places, transactions may have been taxed and regulated but they tended to operate outside bonds of tenure. Slavery, once ubiquitous in Roman and post-Roman Afro-Eurasia, persisted in the Arab world, but was gradually dying out in Christian lands, whether through moral distaste driven by the church or economic prudence.
Rather different demographic and economic patterns survived outside the heartlands of settled communities, around the geographic margins of the region – the Atlantic seaboard, the fringes of the Sahara, the plains, forests, steppes and tundra north of the Black Sea and Carpathian mountains, north and east of the Elbe towards the Arctic Circle – as well as in the areas within the settled regions on the edge of cultivatable land – deserts, mountains, marshes and islands. Many places on the periphery of the region harboured nomadic tribes, shifting Turkish alliances in the Eurasia steppes; Bedouin in the deserts of the Near East; seasonal herdsmen such as the Lapps near and beyond the Arctic Circle. These groups depended on varying degrees of intimacy with their settled neighbours; most of the Bedouin and many of the Turkish nomads had accepted Islam; waves of Turkish invasions from the eleventh to the thirteenth centuries into the Balkans and Near East, followed by the Mongols from the Far East in the thirteenth century, highlighted this relationship. Similar mechanisms of exchange between the central lands and the geographic fringes applied to the non-nomadic peoples of northern Europe, Basques, Irish and the Scandinavians commonly known as the Vikings. In northern and north-eastern Europe, paganism flourished and resisted the cultural penetration of Christianity unenforced by commerce or conquest. Christianity (or Islam) was not necessary for the creation of stable cultural and political institutions. The eastern Baltic only began to be converted in the twelfth and thirteenth centuries. Lithuania remained staunchly pagan until the late fourteenth century and then converted on its own terms for political reasons.
The oldest institution in western Europe in the eleventh century, selfconsciously tracing an uninterrupted history back a thousand years, was the papacy. Originally one of five patriarchs of the early church (Jerusalem, Constantinople, Antioch and Alexandria being the others), the bishop of Rome claimed primacy as the successor to SS Peter and Paul, the guardian of these founding saints’ bones (supposedly buried beneath St Peter’s basilica) and the diocesan of the seat of empire, from the Emperor Constantine (306–37) and the fourth century, a Christian empire. After the Arab invasions of the seventh century, only Rome and Constantinople remained in Christian hands; Jerusalem had fallen to the Muslims in 638. The absence of a western Roman emperor after 476 drew the pope and the eastern, Byzantine, emperor closer together, if in an uneasy relationship. The absence of effective imperial power in Italy had propelled the papacy into a position of temporal authority over the city of Rome and, in theory at least, parts of the central peninsula. Papal spiritual authority was enhanced by its sponsorship of the conversion of the Anglo-Saxons in the seventh century and of the Frisians and continental Saxons in the eighth.