old enemies (Persians, Lombards, Avars, Slavs) and by peoples appearing for the first time in history, the Arabs and the Bulgars. Enemy attacks in this period were not localized to border areas but extended well beyond, even threatening the capital itself. At the same time, the attacks were no longer intermittent or ephemeral in character but took the form of permanent settlements of peoples that transformed into new states, hostile to Byzantium.
Changes can also be observed in the internal structure of the Empire. These changes were dictated by both external and internal conditions. The predominance of small, free farmers, the expansion of military estates and the development of the theme system, brought to completion developments that had started in the previous period.
Changes were noted also in the administration: the state was gradually Hellenised, while the restoration of Orthodoxy after the iconoclast movement, allowed the successful resumption of missionary action among neighbouring peoples and their placement within the sphere of Byzantine cultural influence.
During this period the geographical boundaries of the state were reduced and the Empire was economically weakened following the loss of some of its wealthest regions; however it gained greater linguistic, religious and cultural homogeneity.