On the external front, matters were also turning in Byzantium's favor. In the north, Bulgars and Russians remained recalcitrant, yet had passed through a process of sedentarization. In both cases, but even more so in the case of the Bulgars, they had settled into mostly unitary states, with an interest in a modus vivendi. At the least, they had lost some degree of martial vigor, and that they were sedentary meant that it was easier to fight them on the terms with which Byzantium--itself a sedentary state--was familiar. As well, the Orthodox Christianization of these regions contributed intangibly to a lessening of the civilizational gap.
This is not to mention the southeastern front, Islam. From the mid 800s, the Islamic world was politically riven by rival states. Abbasid caliphs in Baghdad were increasingly unable to exert control over outlying governors, and by the 950s, were rulers only in name. Under the protection of Turco-Persian Buyid Amirs in their own capital, Abbasid territories no longer extended past Iraq. By 970, a rival polity emerged in North Africa. The Fatimids were a Shi'i political dynasty who soon occupied Egypt and moved into Syria as well. Thus, a political conflict carried heavy undertones of confessional strife between Sunnis and Shi'is. An upshot was that the Abbasid forces, or the forces of their protectors, were no longer as able, or inclined, to pursue sustained offensives against Byzantium. Indeed, both the Fatimids and Buyids at times requested Byzantine assistance in their conflicts, and it was because of the political vacuum in the southeastern Anatolia-Syria-Lebanon region--the seam between Abbasids and Fatimids--that John Tzimisces was able to recapture areas such as Antioch.
These favorable external conditions did not persist, especially in the East. Ever since the 900s, the Turks had been looming on the eastern fringes of the Islamic world. Mahmud of Ghazna had established the first Turco-Islamic state in Khurasan in the 940s. In the early 1000s, though, a more serious Turkish migration into Islamic lands began. Based on armies of mounted light cavalry able to fire arrows while at a gallop, they bested the armies put against them. Under the Seljuk dynasty originating in Iran, they came through the Abbasid heartlands in the 1040s, reigning supreme in Baghdad by 1050. Now, there was a strong Sunni state to rival the Shi'ites in Egypt and Syria. Along with this polity came less disciplined Turcoman tribes, who the Seljuk sultans had trouble restraining. Indeed, the Seljuk sultan Alp Arslan had pursued peaceful relations with the Byzantines in the 1050s and 1060s so that he could shore up his position in Mesopotamia and go on the offensive against the Fatimids in Syria. The tribes, however, began plundering and pasturing in Asia Minor from the late 1050s. At times, segments of Turkic tribes were brought further into Anatolia when they were hired as mercenary soldiers by Byzantine generals. When these somewhat Islamized Turkic groups began to capture Byantine posts and plunder Greek population centers, the Seljuk Sultan Alp Arslan was eventually forced to defend these kinsmen who now came under Byzantine military pressure.
The Byzantine state the Seljuks confronted, though, was not nearly the same as it had been in the period of Basil II. If there was a 'Byzantine system'-- comprising Theme armies based on peasant smallholders in Anatolia, led by generals loyal to their emperors, who in turn restrained the Anatolian aristocracy and remained financially frugal--this system broke down beginning in 1025. The Anatolian elites, along with the Constantinople civil aristocracy, never transcended their self-centered interests, and were content to deplete the army in pursuit of material wealth. And, there was no one to stop them; post- Basil emperors were either the creatures of the incompetent Zoe, or antagonistic towards the army. Thus, the disastrous results of 1071 should not be surprising. Romanus' army was not even Greek in composition, and to the extent that it was coherent, it could not match the mobile, mounted forces of the Turks. Once again, the conflict between a sedentary civilization and a semi- nomadic, migratory one signaled the decline of the settled protagonist. Just as this was reminiscent of the Germanic migrations into the Roman world, the process of de-Hellenization and slamization that inexorably progressed through Anatolia from the 1070s to 1300 constituted a similar civilizational shift, only now, the newcomers did not take on the host- faith, but spread their own. The Turkish period of Islamic history--as distinct from the Arab and Persian one--was fully under way.
As an extremely important footnote, in 1054 there occurred an event of extreme cross-cultural importance. Latin Christianity, whose spiritual leader was the Pope, had for the past two-hundred years taken a very different course from the Greek Orthodox Christianity of the Byzantine Empire. Whereas the Pope articulated a position of autonomy from, and even supremacy over, secular rulers in the West, the Byzantine Church was almost a department of state. Patriarchs were appointed by the Emperor, and carried out state policy, theological or otherwise. Beyond that, the Greek mind did not abjure the kind of philosophical-theological speculation so abhorrent to Latin Christina authorities, just as the Greeks considered their Latin brothers as no more than a continuation of the Barbarian German strain of cultural degradation. In addition, while the Pope saw himself as the vicar of Christ and leader of Christendom on earth, the Patriarch in Constantinople usually considered the Bishop of Rome as little more than a primus inter pares (first among equals). In a quite more concrete manner, Byzantium and the Papacy had conflicting goals in the Italian peninsula. While the Papacy wished to maintain and increase the power and size of the Papal States, Byzantine leaders had never given up on their shrinking possessions on the peninsula. This often brought the two into tension. By the 1050s, though, a new threat emerged, in the form of the Normans who controlled southern Italy. Pope Leo IX actually led an army against them in 1053, and was defeated and captured near Civitate. Supposedly, the Pope should have received Byzantine assistance--an impossibility given the (lack of) military policy at Constantinople. In any event, in 1054, a Papal legation headed by the anti-Greek Cardinal Humbert of Mourmoutiers was sent to Constantinople to deal with a few disagreements in doctrine, as well as the much more important mater of an anti-Norman alliance. The Patriarch, Michael Cerularius, was equally anti-Latin, and treated his colleagues as a superior would treat an irrelevant inferior. This infuriated the legates of God's vicar on earth. Over four months of no progress, relations deteriorated, and on July 16, 1054, Humbert and his followers excommunicated the Patriarch, and, by implication, the entire Eastern Church. Oddly enough, they did this at a time when Leo IX had died and a new Pope had not been elected. Still, though it was not conceived as permanent--excommunications had occurred before--the 1054 Schism remained. The rift continues today.