Koine Greek (ἡ κοινὴ διάλεκτος, hē koinḕ diálektos, lit. 'the common dialect'), also variously known as Hellenistic Greek, common Attic, the Alexandrian dialect, Biblical Greek, Septuagint Greek or New Testament Greek, was the common supra-regional form of Greek spoken and written during the Hellenistic period, the Roman Empire, and the early Byzantine Empire. It evolved from the spread of Greek following the conquests of Alexander the Great in the fourth century BC, and served as the lingua franca of much of the Mediterranean region and the Middle East during the following centuries. It was based mainly on Attic and related Ionic speech forms, with various admixtures brought about through dialect levelling with other varieties.
Koine Greek included styles ranging from conservative literary forms to the spoken vernaculars of the time. As the dominant language of the Byzantine Empire, it developed further into Medieval Greek, which informed Modern Greek.
