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.
Final War of the Roman Republic
With the end of the last Republican civil war, the Republic was replaced by the Empire. The reign of Augustus would usher in the golden era of Roman culture and produce a stability which Rome had not seen in over a century. With Rome in control of the entire Mediterranean world, a peace would reign in the Roman world for centuries after the death of Augustus: the so-called Pax Romana (Roman Peace).