<P> The 8th and early 9th centuries were also dominated by controversy and religious division over Iconoclasm, which was the main political issue in the Empire for over a century . Icons (here meaning all forms of religious imagery) were banned by Leo and Constantine from around 730, leading to revolts by iconodules (supporters of icons) throughout the empire . After the efforts of empress Irene, the Second Council of Nicaea met in 787 and affirmed that icons could be venerated but not worshiped . Irene is said to have endeavoured to negotiate a marriage between herself and Charlemagne, but, according to Theophanes the Confessor, the scheme was frustrated by Aetios, one of her favourites . </P> <P> In the early 9th century, Leo V reintroduced the policy of iconoclasm, but in 843 empress Theodora restored the veneration of icons with the help of Patriarch Methodios . Iconoclasm played a part in the further alienation of East from West, which worsened during the so - called Photian schism, when Pope Nicholas I challenged the elevation of Photios to the patriarchate . </P> <P> The accession of Basil I to the throne in 867 marks the beginning of the Macedonian dynasty, which would rule for the next two and a half centuries . This dynasty included some of the most able emperors in Byzantium's history, and the period is one of revival and resurgence . The Empire moved from defending against external enemies to reconquest of territories formerly lost . </P> <P> In addition to a reassertion of Byzantine military power and political authority, the period under the Macedonian dynasty is characterised by a cultural revival in spheres such as philosophy and the arts . There was a conscious effort to restore the brilliance of the period before the Slavic and subsequent Arab invasions, and the Macedonian era has been dubbed the "Golden Age" of Byzantium . Though the Empire was significantly smaller than during the reign of Justinian, it had regained significant strength, as the remaining territories were less geographically dispersed and more politically, economically, and culturally integrated . </P>

What group attacked the eastern border of the byzantines