In , emperor Teodosius, from Hispanic ascendence, divided the Roman Empire into two parts. Western stayed under the control of his son Honorio and Eastern for Arcadio. The was richer and was not affected by Germanic invasion as the Western Empire. Thanks to this fact Eastern Empire, whose capital city were (an ancient Greek colony called that was embellished by the emperor ).

Since emperor came to power, we can talk about instead of Eastern Roman Empire. He ruled the Empire with his wife (both appear in two wall in the Italian church of S. Vital, in the city of ). He tried to the Roman Empire, so through his generals, as Belisario, he conquered , almost whole and the . Two main characteristics of Justinian period was the great of the emperor or (he was the , and head of the Empire) and one of the most important facts in Laws History, such as the compilation of all the Roman rules and laws known until the moment.

Justinian period was the most and ages of the Byzantine Empire. Since Justinian's death in 565, the territories began to due to various causes. In Italy, (a Germanic tribe came from North Europe through Danubian river valley), conquered Byzantine territories. In Hispania, leaded by their king Leovigildo expelled them from southern part of the Iberian peninsula. Finally, expansion caused Byzantines lost the Eastern and Southern parts of their territories.
By century Byzantine Empire was only the Western part of the anatolian peninsula and the South of the Balcanic peninsula (what nowadays is Greece, Albania and the south of Bulgaria). By the century, 50 years before Constantinople was conquered by the Turks, the only part truly controlled by the Byzantine power was . Finally, at , the Turks leaded by the sultan Mehmet II, came into the "New Rome".

The highest authority of the Muslim Empire was the . The first caliphs were direct of the . At first, the Muslim armies controlled the entire Arabian peninsula. In , Caliph was assassinated and the family took power.
During Umayyad period the title of caliph became . The Umayyads moved the capital of the empire to and conquered many territories from Persia to the peninsula, which was under control of the , with their king .
In a rebellion ended the Umayyad dynasty and one new one came into power, the family. They moved the capital to from .
Finally, internal fighting broke up the empire. By XIIIth the most powerful people of the Muslim world was , who conquered Empire by come into the capital city in .