The end of the eleventh century has aptly been described as a ‘turning point’ in the history of Byzantium. Under the pressure of the incursions of Normans, Petchenegs and later Crusaders in the European themes and of the Turks on the eastern frontier and in Anatolia, the defences of the empire began to buckle. Debasement and inflation, a constant threat throughout the century and much more serious after 1070, were fuelled by the need to find more cash to pay the ever increasing mercenary forces of the Byzantine army. The great days of victory of the late tenth and early eleventh century were long since past, and commentators of the period sought long and hard for explanations for the failure of Byzantine military forces. The provincial aristocracies, already flexing their muscles in the tenth century, increasingly controlled access to the imperial power, especially after the death of the Empresses Zoe and Theodora, the last representatives of the Macedonian line.

It was yet another scion of a powerful house (or rather group of houses), Alexios Komnenos, who, by managing to obtain the imperial office which he achieved by coup d'état in 1081, instituted a more stable period of imperial government which was to last until the end of the twelfth century. The changes which he introduced in the style of government, in the financial and judicial organisation of the empire and in the church have often led to his being characterised as a great reformer.