Diocletian was an emperor of Rome. He ruled from 284 to 305 CE. Diocletian brought stability for a time to an empire that was in something of a state of disarray when he came to power. Diocletian brought the Roman army under control and improved the security of the empire. Perhaps his most important legacy is that he laid out policies that were to form the basis for the creation of the Eastern Roman Empire. He did this mainly by splitting the empire into different parts, each of which would be ruled by a separate ruler, though he himself would be the overall ruler. This empire came to be called the Byzantine Empire and it outlasted the Western Roman Empire by centuries.