The document provides background information on the Byzantine Empire. It describes how the Roman Empire was originally centered around the Mediterranean but faced internal and external threats over time. Emperor Diocletian divided the empire into western and eastern halves to make it easier to govern. Constantine later moved the capital to Constantinople in Turkey. The western half of the empire continued to decline due to invasions, while the eastern half grew stronger under emperors like Justinian who reconquered territory and standardized the legal system. The Byzantine Empire had Constantinople as its capital and spoke Greek, with Orthodox Christianity becoming its dominant religion.