what was the power structure of the byzantine empire
Byzantine army From the seventh to the 12th centuries, the Byzantine army was among the most powerful and effective military forces in the world â€“ neither Middle Ages Europe nor (following its early successes) the fracturing Caliphate could match the strategies and the efficiency of the Byzantine army. Restricted to a largely defensive role in the 7th to mid-9th centuries, the Byzantines developed the theme-system to counter the more powerful Caliphate. From the mid-9th century, however, they gradually went on the offensive, culminating in the great conquests of the 10th century under a series of soldier-emperors such as Nikephoros II Phokas, John Tzimiskes and Basil II. The army they led was less reliant on the militia of the themes; it was by now a largely professional force, with a strong and well-drilled infantry at its core and augmented by a revived heavy cavalry arm. With one of the most powerful economies in the world at the time, the Empire had the resources to put to the field a powerful host when needed, in order to reclaim its long-lost territories.
Byzantine art A number of states contemporary with the Byzantine Empire were culturally influenced by it, without actually being part of it (the "Byzantine commonwealth"). These included the Rus, as well as some non-Orthodox states like the Republic of Venice, which separated from the Byzantine empire in the 10th century, and the Kingdom of Sicily, which had close ties to the Byzantine Empire and had also been a Byzantine possession until the 10th century with a large Greek speaking population persisting into the 12th century. Other states having a Byzantine artistic tradition had oscillated throughout the Middle Ages between being part of the Byzantine empire and having periods of independence, such as Serbia and Bulgaria. After the fall of the Byzantine capital of Constantinople in 1453, art produced by Eastern Orthodox Christians living in the Ottoman Empire was often called "post-Byzantine." Certain artistic traditions that originated in the Byzantine Empire, particularly in regard to icon painting and church architecture, are maintained in Greece, Cyprus, Serbia, Bulgaria, Romania, Russia and other Eastern Orthodox countries to the present day.