Both Constantine and the Christian emperors who succeeded him attempted to manage the church and Christian orthodoxy through ecumenical councils, new laws, and increased bureaucratization in the Roman government. The two great superpowers of Late Antiquity, the Byzantine Empire and the Sasanian Empire, vied for supremacy in the fifth and sixth centuries.

After the political tumult of the third century, the emperor Constantine reinvigorated the Roman Empire by establishing a new capital in Constantinople and embracing Christianity. This new religious culture resulted in the neglect of traditional Roman polytheism, and the empire’s eastward shift came at the expense of the western empire.

ecumenical councils — meetings organized by emperors that gathered Christian bishops from around the empire to settle matters of doctrine within the Church. Late Antiquity — a transitional period between the ancient and medieval worlds that occurred from roughly 150 to 750 CE. Code of Justinian — a legal project carried out by Emperor Justinian to compile and edit Roman edicts issued from the second to the sixth century CE. foederati — foreign states and tribes that were given semiautonomy as Roman allies in exchange for pledging military service to the Roman Empire.