History of the Roman Empire
Theodosius was the last Emperor who ruled over the whole Empire. After his death in 395, he gave the two halves of the Empire to his two sons Arcadius and Honorius; Arcadius became ruler in the East, with his capital in Constantinople, and Honorius became ruler in the West, with his capital in Milan and later Ravenna. The Roman state would continue to have two different emperors with different seats of power throughout the 5th century, though the Eastern Romans considered themselves to be the only ones who were fully Roman. Latin was used in official writings as much as, if not more than, Greek and the two halves were nominally, culturally and historically, if not politically, the same state.
List of Roman emperors
In the late 3rd century, after the Crisis of the Third Century, Diocletian formalised and embellished the recent manner of imperial rule, establishing the so-called Dominate period of the Roman Empire. This was characterised by the explicit increase of authority in the person of the Emperor, and the use of the style ("Our Lord"). The rise of powerful Barbarian tribes along the borders of the empire and the challenge they posed to defense of far-flung borders and unstable imperial succession led Diocletian to divide the administration geographically of the Empire in 286 with a co-Augustus. In 330, Constantine the Great established a second capital in Byzantium, which he renamed Constantinople. For most of the period from 286 to 480, there was more than one recognised senior emperor, with the division usually based in geographic terms. This division was consistently in place after the death of Theodosius I in 395, which historians have dated as the division between the Western Roman Empire and the Eastern Roman Empire. However, formally the Empire remained a single polity, with separate co-emperors in the separate courts. The fall of the Western Roman Empire, and so the end of a separate list of emperors below, is dated either from the date of 476 when Romulus Augustulus was deposed by Odoacer who became King of Italy, or the date of 480, on the death of Julius Nepos, when Eastern Emperor Zeno ended recognition of a separate Western court. In the period that followed, the Empire is usually treated by historians as the Byzantine Empire governed by the Byzantine Emperors, although this designation is not used universally, and continues to be a subject of specialist debate today.