Surviving Latin literature consists almost entirely of Classical Latin in its broadest definition. It includes a polished and sometimes highly stylized literary language sometimes termed Golden Latin, which spans the 1st century BC and the early years of the 1st century AD. However, throughout the history of ancient Rome the spoken language differed in both grammar and vocabulary from that of literature, and is referred to as Vulgar Latin. In addition to Latin, the Greek language was often spoken by the well-educated elite, who studied it in school and acquired Greek tutors from among the influx of enslaved educated Greek prisoners of war, captured during the Roman conquest of Greece. In the eastern half of the Roman Empire, which became the Byzantine Empire, the Greek Koine of Hellenism remained current and was never replaced by Latin. It continued to influence the Vulgar Latin that evolved into the Eastern Romance languages.