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.
Sack of Rome (410)
The sack was a culmination of many terminal problems facing the Western Roman Empire. Domestic rebellions and usurpations weakened the Empire in the face of external invasions. These factors would permanently harm the stability of the Roman Empire in the west. The Roman army meanwhile became increasingly barbarian and disloyal to the Empire. A more severe sack of Rome by the Vandals followed in 455, and the Western Roman Empire finally collapsed in 476 when the Germanic Odovacer removed the last Western Roman Emperor, Romulus Augustulus, and declared himself King of Italy.