Our series on Empires takes us to the Byzantine Empire at its greatest extent, around 600ad.
The Roman Empire is debatably the greatest empire that ever existed. It controlled the entire Mediterranean Basin for Centuries. Signs of decadence started to appear when tribal groups coming from Eastern and Central Europe forced a series of retreats. Around the same time, the Empire was split into an Eastern and Western Regions, who then became independent. The Eastern Empire, based in Constantinople, the former Byzantium, became known later as the Byzantine Empire. While the Western Empire fell in 476, the Byzantine Empire prevailed for much longer, even recovering some old Western Empire lands in North Africa, Italy and Illyria.
The downfall of the Byzantine Empire happened by attrition, mostly at the expense of Arab and Turkish states. By 1453, the Ottoman state, which controlled all of Anatolia, took Constantinople in what can be seen as the end of the Roman Empire and the start of the Ottoman Empire.
More on the Byzantine Empire