Who was the first emperor of Eastern Rome

The firstemperor of the eastern part of the Roman Empire was Diocletian who created aeastern and a western part of this empire in 286. However, it has to be notedthat these were administrative units of a single Roman Empire, which,Diocletian stressed, was indivisible. He created a co-emperorship with himselfin charge of the east and Maximian in charge of the west. After Diocletian there were alternationsbetween periods of sole emperorship with one emperor in charge of the wholeempire and periods with co-emperorships with one co-emperor in charge of theeast and one in charge of the west.Historiansconsider the eastern and western parts of the Roman Empire to have become splitafter the death of Theodosius I, the last sole emperor, in 395. He gave the westernpart to his son Honorius, and the eastern part of his other son Arcadius. Theempire became split for two reasons. One was that the co-emperors were youngand inexperienced and powerful politicians in the east and the west tookadvantage of this to conspire against each other. There was also a plot in thewest to seize some of the land of the east. The other reason is that the Germanicinvasions of the western part of the empire begun soon afterwards, in 406.These invasions were the beginning of the fall of the western part of the RomanEmpire.