By the end of this section, you will be able to: Explain how and why the political focus of the Roman Empire shifted eastward during Late Antiquity Discuss how the adoption of Christianity as the official religion of the Roman Empire altered Mediterranean society Explain the collapse of Roman authority in the West, including the role of Germanic migrations and invasions From the third through the seventh centuries CE, the culture of the Roman Empire transformed itself profoundly and in fundamental ways. The rise of Christianity marked a seminal moment, and from the time of the emperor Constantine in the fourth century, the government advocated monotheism, the worship of one God to the exclusion of others. With a Christian government and a new capital at Constantinople in the eastern Mediterranean, the Byzantine Empire grew from the old Roman state. At the same time, the fracturing of the Roman Empire’s government led to various new regional alliances and rivalries. Germanic kingdoms flourished in the West, while the Byzantines attempted to maintain order among the burgeoning Christian population within their borders. The Roman Empire’s eastward shift epitomized the major cultural changes occurring during this period. Because of these shifts, Late Antiquity has been characterized as a transitional period between the ancient and medieval worlds that occurred from roughly 150 to 750 CE. On the one hand, Late Antique culture remained influenced by the classical past, with the maintenance of certain ancient institutional values. While still calling themselves “Romans,” the Byzantines simultaneously attempted to maintain Christian orthodoxy. On the other hand, the appearance of new religious identities and the breakdown of the Roman state led to conflicts among different regional and cultural groups. The empire’s borders were in constant flux, and its territory slowly diminished as numerous powers vied for regional dominance.