Byzantine Greek refers to the form of the Greek language that was spoken during the Byzantine Empire (AD 330-1453) in Eastern Europe and the Mediterranean. This language is also known as Medieval Greek, Byzantine Greek, or New Testament Greek. Other synonyms for Byzantine Greek include Hellenistic Greek, Koine Greek, and Polytonic Greek. Hellenistic Greek refers to the type of Greek spoken during the Hellenistic period (c. 323 to 31BC), and Koine Greek refers to the common dialect spoken in the Eastern Mediterranean region during the same period. Polytonic Greek, on the other hand, is a system of writing Greek that uses multiple accents and diacritical marks.