The Roman and Byzantine Empires were used by the American Founding Fathers to set a framework for a new (or more aptly “updated”) form of government after the Revolution. Although the United States was always called a melting pot, many of our citizens have never really embraced the idea that we’re stronger through our diverse cultures, many languages, and innumerable ethnicities. The Roman Empire certainly experienced its fair share of racism — but they also embraced other cultures much more easily than we do.
Because the building of these extraordinary empires occurred on the premise of assimilation — but not total assimilation, as conquered territories were originally allowed to keep their own customs and religions — there were also many languages commonly spoken across the Byzantine territories. These included aging Latin, Koine Greek, and Medieval Greek.
The Byzantine Empire continued to embrace much of what made the Roman Empire strong, but one of its great failings was the lack of religious diversity. Christianity was a mainstay of traditional beliefs, which ultimately reduced diversity and fomented distrust of outsiders (sound familiar?). Latin was already spoken in fewer regions, and most Byzantine territories relied on Greek. We associate Latin with the Catholic Church, but in fact Greek was most commonly used there as well.
Greek was eventually associated with scholars, artistic endeavors, and the language of trade. What English is today, Greek was yesterday. Of course, there were innumerable dialects spoken over a massive space. Koine and Medieval Greek became the most commonly spoken. Before Koine came along, Attic Greek pervaded.
It is widely considered possible that Emperor Justinian I may have been the last to speak Latin. His Corpus Juris Civilis was written in Latin, and he believed it was an important language that should be taught and used. Shortly after his time as emperor, it fell out of use entirely. Latin was revived several times throughout Byzantine history, though, especially during the 10th and 11th centuries.