What place did Byzantium occupy in the world at the beginning of the Middle Ages? Would the assessments of contemporaries

What place did Byzantium occupy in the world at the beginning of the Middle Ages? Would the assessments of contemporaries be fair if Constantinople was considered the center of the inhabited world?

At the beginning of the Middle Ages, the Byzantine Empire was the most developed and powerful state. After the destruction of the Western Roman Empire, only Constantinople was the stronghold of ancient civilization, culture and traditions. Moreover, it is the most developed city of that time, because all other great cities were either destroyed or conquered by the Barbarian tribes. Therefore, the opinion that Constantinople is the center of the inhabited world can be considered reliable.