Byzantium. The history of the disappeared empire

Having arisen on the wreckage of the Great Roman Empire, Byzantium throughout its more than thousand -year history was an arena of constant invasions, siege and wars. The border of the West and the East, the symbol of the Christian world - Constantinople - attracted the invaders, striking with his wealth and splendor. How did the Byzantine Empire, which once belonged to half the world, despite all the shocks, lasted amazingly long and why in the end it disappeared almost without a trace, as if disappeared? Neither the powerful army, nor the skill of its politicians, nor the impregnable walls of Constantinople, nor the belief that God will not leave the first Christian empire, which spread the new religion, not only in its vast territory, but also in neighboring states, saved the ancient power. The British historian Jonathan Harris says about how originated in the world and the Byzantium ruled the world