This makes no sense and you're just not familiar with the history of that period. The fall of Rome merged into the rise of the second Rome, Byzantium, under Constantine which was the first Christian empire and the longest lasting empire in history. It was the preeminent cultural center of the world at its height until the Ottomans conquered it in 15c. The Vatican was part of the empire and became a papal state in the 8c.
This makes no sense and you're just not familiar with the history of that period. The fall of Rome merged into the rise of the second Rome, Byzantium, under Constantine which was the first Christian empire and the longest lasting empire in history. It was the preeminent cultural center of the world at its height until the Ottomans conquered it in 15c. The Vatican was part of the empire and became a papal state in the 8c.