By the early eleventh century, the Byzantine empire stretched from the Danube and Adriatic, with some outposts still retained on the mainland of Italy (at Bari, for instance), to the Taurus and Anti-Taurus mountains of eastern Anatolia and a few strongholds in northern Syria, such as Antioch. Seemingly dominant, culturally, commercially and politically, in fact the empire had only recently reasserted its position in northern Syria and the northern Balkans, where the previously independent Bulgarian state had been painfully annexed by Emperor Basil II, ‘the Bulgar Slayer’ (976–1025), and Serbian separatist tendencies neutralized. This hegemony did not last long. In the mid-1050s, Turkish tribes led by the Seljuk family had invaded the Near East, becoming the effective rulers in Baghdad. In 1071, the Seljuks invaded Anatolia, defeating and capturing the Byzantine emperor, Romanus IV Diogenes, at the battle of Manzikert. With their frontier defences breached, the Byzantines soon lost the interior of Anatolia, the Seljuks even establishing their Anatolian capital at Nicaea, within striking distance of Constantinople itself. Behind the Seljuk conquest of Anatolia other Turkish tribes took advantage of the political chaos to exploit the towns and settled agrarian economy of the region. The chief of these groups were the Danishmends, who established a so-called ghazi (i.e. holy warrior) state to the north-east of the peninsula. At much the same time, other nomadic and semi-nomadic tribes penetrated Byzantium’s Balkan frontiers. Twenty years earlier, the Greeks had to accept the settlement of the Pechenegs south of the Danube in north-eastern Bulgaria, while another steppe people, the Cumans, established themselves just to the north of the Balkan frontier. Across the Adriatic, the final Byzantine holdings were snuffed out by the new power in the region, Norman adventurers led by Robert Guiscard. Bari, the last stronghold, fell in 1071. Guiscard followed up his victory by invading the Balkans. Only with the accession of the military usurper Alexius I Comnenus was the Norman threat repulsed at Durazzo (now Durres on the Adriatic coast of Albania) in 1085 and the Pechenegs finally defeated, at Mount Levounion (at the mouth of the Maritsa in southern Thrace near the modern Turco–Greek border) in 1091. Apart from the Italian possessions, only the losses to the Seljuks in Anatolia and northern Syria remained to be restored. That is where, in the eyes and strategy of Alexius I, the appeal to the west he made in 1095 and the First Crusade came in.
The shifting fortunes of Byzantium in the eleventh century were mirrored by the disorder in the Islamic Near East following the Seljuk invasions of the 1050s. After seizing control of the Baghdad caliphate in 1055, their leader receiving the apt title of ‘sultan’ (sultan is Arabic for power), the Seljuk Turks pressed westwards. After defeating the Greeks in 1071, they annexed most of Syria and Palestine by 1079. However, despite the appearance of unity, the Seljuks presided over a loose, often fractious confederation of regional powers, such as the more or less independent sultanate of Rum, i.e. Anatolia, and city states, such as Mosul, Aleppo, Antioch (taken in 1084/5), Damascus and Jerusalem. These old Arab cities, while often owing allegiance to one or other of a series of competing Seljuk lords, were often controlled by Turkish military commanders (atabegs) whose authority rested as much in their personal mercenary bands, often of slave troops (mamluks), as on higher Seljuk approval. Everywhere, ethnic and religious diversity complemented the alienation of ruled – whether town-dwellers, rural cultivators or Bedouin or steppe nomads – from ruler. In parts of Syria, immigrant Turkish Sunnis ruled indigenous Shia populations or exerted control over local Arab nobles. In Cilicia and northern Syria, significant religiously and ethnically distinct Armenian communities were squeezed between the competing powers of Byzantium, Arabs and Turks. Across this area and in the Jazira (modern northern Iraq) the political uncertainties offered opportunities for Kurdish as well as other Turkish incomers. Similar dislocation characterized the Fatimid caliphate of Egypt, which contested with the Seljuks ascendancy over southern Palestine. In Egypt, the Shia rulers dominated the majority Sunni inhabitants through powerful chief ministers, called viziers, who were often neither Egyptian nor Arab, but Turks or Armenians. The Near East presented no harmonious spectacle of civilized peace. The Turkish invasions from the 1050s destabilized the region, introducing an alien ruling elite backed by military coercion, causing as much if not more mayhem and disruption than the crusaders were able to achieve.
Elsewhere in the Muslim Mediterranean, the political pendulum was swinging towards Christian powers. After the implosion through internecine feuding of the Cordoba caliphate in 1031, Muslim Spain, al-Andalus, was ruled or fought over by competing so-called taifa or ‘party’ kings. Their weakness and disunity allowed Christian rulers north of the Ebro to take advantage of the lucrative offers of pay and alliance to extend their power southwards, a process driven by profit, not religion, but later given the accolade of the ‘Reconquest’ or reconquista, in largely propagandist reference to the Arab conquest of the eighth century. By the end of the eleventh century, distinctive political identities had been assumed by five Christian statelets: Catalonia; Aragon; Navarre; León; and Castile. These were joined in the 1140s by the creation of Portugal following conquests between the Duero and Tagus rivers along the Atlantic seaboard. Despite a Muslim counter-attack led by a puritanical north African Muslim fundamentalist sect, the Almoravids (c.1086–1139), these Christian principalities managed to exploit the enfeebled political system of their indigenous Muslim neighbours to forge lasting ascendancy in the northern half of the peninsula, which provided the basis for the sweeping conquests of the thirteenth century.
Across the western Mediterranean, between 1060 and 1091, the island of Sicily, a former Byzantine territory in Muslim hands since the later ninth century, was conquered by armies commanded by lords of Norman French extraction whose presence in the region exemplified the fluidity of high politics where skill in battle plus a private army could propel ambitious warriors, in western Europe as much as in the Near East, to unpredicted eminence. The collapse of an independent post-Carolingian kingdom of Italy in the tenth century had opened the north of the peninsula to German invasion and the assertion of civic independence by the commercial and manufacturing cities and entrepôts of the Po valley (Milan, Venice), Liguria (Genoa) and Tuscany (Florence, Pisa). In the south, Byzantine rule in Apulia and Calabria rubbed uneasily against squabbling local dynasts in Capua, Salerno and Benevento, providing plenty of opportunities for hired professional fighters. The most militarily and politically successful of these came from Normandy, a duchy in northern France with a surplus of arms-bearers and an insufficiency of land, patronage and preferment. Normans, attracted perhaps by a familiar pilgrimage route but certainly by the prospects of profit and improved status, began making their presence felt in south Italian politics from the 1020s. By 1030, one contingent had acquired a permanent hold on Aversa between Naples and Capua. Within thirty years, Norman warlords dominated the area. After a disastrous attempt by Pope Leo IX to put papal theories of temporal jurisdiction into practice by trying to oust them ended in a crushing papal defeat at Civitate in 1053, the Norman lords acquired titles and respectability as the reforming papacy sought protectors. In 1059 Pope Nicholas II (1059–61) recognized Richard of Aversa as prince of Capua and Robert Guiscard as prospective ruler of Byzantine Calabria and Apulia and Muslim Sicily. To reinforce the honour, when Robert Guiscard’s brother, Roger, began the conquest of Sicily in 1060, the enterprise was awarded a papal banner.