History of the East–West Schism
Disunion in the Roman Empire further contributed to disunion in the Church. The Emperor Diocletian famously divided the administration of the eastern and western portions of the Empire in the early 4th century, though subsequent leaders (including Constantine) aspired to and sometimes gained control of both regions. Theodosius the Great, who established Nicene Christianity as the official religion of the Roman Empire (see Edict of Thessalonica), was the last Emperor to rule over a united Roman Empire. Following his death in 395, the division into western and eastern halves, each for a few decades still under its own Emperor, was never reunited.
Herules
Along with many other people they reappear in the written records as one of many groups from the east who were struggling for supremacy on the left bank of the middle Danube after the death of Attila, in the area stretching from modern Bavaria to modern Hungary. They established their own kingdom and many joined Odoacer, who deposed the last Western Roman Emperor Romulus Augustus in 476 AD. They became well known both as soldiers in various Roman armies, in the Italian kingdom of Odoacer, and as sea raiders on the Atlantic coast, before fading out of history. The Danubian kingdom broke up and remnants settled in the Balkans and other places. The last known political entity which was described as Herulian seem to have been in the area of modern Belgrade in the 550s, as a settlement within the Roman Empire and under Roman control.