While the Roman Empire was officially bilingual (Latin and Greek), the Eastern Roman Empire, or Byzantine Empire, developed a distinct Byzantine Greek language. This language evolved from Koine Greek, the common language of the Hellenistic period, and incorporated elements of Latin and other languages.
While Byzantine Greek shared similarities with modern Greek, it also contained unique features and vocabulary. This language remained the dominant tongue of the Byzantine Empire for centuries, used in administration, literature, and daily life.