Culture of ancient Rome
The Roman Empire, at its height (c. 117 CE), was the most extensive political and social structure in western civilization. By 285 CE the empire had grown too vast to be ruled from the central government at Rome and so was divided by Emperor Diocletian into a Western and an Eastern Empire. The Roman Empire began when Augustus Caesar became the first emperor of Rome (31 BCE) and ended, in the west, when the last Roman emperor, Romulus Augustulus, was deposed by the Germanic King Odoacer (476 CE). In the east, it continued as the Byzantine Empire until the death of Constantine XI and the fall of Constantinople to the Ottoman Turks in 1453 CE. The influence of the Roman Empire on western civilization was profound in its lasting contributions to virtually every aspect of western culture.
Byzantine Empire under the Theodosian dynasty
Theodosius I was granted rule of the Eastern Roman provinces by the previous Emperor, Gratian of the Valentinian dynasty, due to Gratian having inherited the entire Empire from his predecessor Valens in 378. Gratian would continue to rule the Western Roman Empire until 383. After the deaths of Gratian and his successor Valentinian II, Theodosius became the last emperor to rule over both the eastern and the western halves of the Roman Empire 392-395.