The ancient Roman Empire is divided into two parts, an Eastern and a Western, the Eastern remained subject to successors of Constantine, whose capital was at Byzantium. Byzantine is therefore employed to designate this Eastern survival of the ancient Roman Empire. Byzantium was the Christian buffer of the spread of Islam into Europe. Justinian the First marks the end of the Roman Empire and the beginning of the Byzantine Empire. What happened between the years of ca. 750-900? In 750, the empire was at its lowest point and everything was in bad shape. Unit of army called Theme system was created that had all the trained soldiers to fight at a specific region. At the end, the theme system did, however work and Constantine V created a mobile field army. .
The fear of idolatry that haunted the Byzantines broke out in iconoclasm between 726-843, the imperially sponsored wholesales destruction and obliteration of all art that depicted sacred figures, and the violent persecution of its opponents. Religious art was limited mainly to images of the cross and of symbolic birds and plants. Perhaps, the most disagreeable character of all the great Byzantine women was Irene. She is honored as a saint in the Greek Church because at the Seventh General Synod of Nicaea, she obtained important concessions in the matter of the veneration of images. "Though the adoration of images as well as other abusive practices of veneration, which had already been condemned as idolatrous, were again wholly forbidden, prostrate veneration, incense, and candles were permitted." She was also married to emperor Leo IV in 775-785. Without empress Irene, the icon would not be restored.
The Iconoclasts represented a principle, which we know to have been forced into the Greek-Byzantine world as something foreign. The Byzantine appear so modern precisely because they were permeated with rationalistic anti-ecclesiastical sentiments.