Between 100-600 the classic Roman empire has gone in and out of western and eastern unification, a change in religious belief, and centralized rule has stayed constant.
Roman ruler Diocletian split the Roman empire into two eastern and western regions to maintain an efficient government. After his rule Constantine decided to reunite the two under one rule, but also move the capitol to the east for strategic purposes. This allowed Germanic tribes to migrate into the east when they were attacked by the Huns. Germanic migrations combined with the lack of leadership led to the collapse of the east. Later under Justinian rule troops were sent to regain eastern Rome, but the land was again lost after his death.
Rome also had a change in their religious beliefs. Before Constantine Rome had polytheistic beliefs, and the practice of Christianity was outlawed. During Constantine’s rule, he put through the Edict of Milan. The edict made the practice of Christianity legal, and led to the public practice of Christianity. Soon afterwards, Constantine converted to Christianity, and justified his rule with caesaropapism. During Constantine’s rule Rome’s primary religion became Christianity. Throughout 100-600 Rome kept its centralized government. The barracks emperors was a period of fifty years where Rome had over twenty rulers. Next came Diocletian, Constantine, and Justinian. The Roman empire was too big to governed by a decentralized rule. Throughout 100-600 the Roman empire had fluctuation in its eastern and western unification, they converted to Christianity, and throughout this period they had a centralized rule.