Proto-Greek language

The Proto-Greek language (also known as Proto-Hellenic) is the assumed last common ancestor of all known varieties of Greek, including Mycenaean Greek, the ancient Greek dialects (i.e., Attic, Ionic, Aeolic, Doric, Ancient Macedonian and Arcadocypriot) and, ultimately, Koine, Byzantine and Modern Greek. The unity of Proto-Greek would have ended as Hellenic migrants, who spoke the predecessor of the Mycenaean language, entered the Greek peninsula sometime in the Neolithic or the Bronze Age.

The evolution of Proto-Greek could be considered within the context of an early Paleo-Balkan sprachbund that makes it difficult to delineate exact boundaries between individual languages. The characteristically Greek representation of word-initial laryngeals by prothetic vowels is shared, for one, by the Armenian language, which also seems to share some other phonological and morphological peculiarities of Greek; this has led some linguists to propose a hypothetically closer relationship between Greek and Armenian, although evidence remains scant.

Proto-Greek is mostly placed in the Early Helladic period (3rd millennium BC), i.e. towards the end of Neolithic Europe.Russell Gray and Quentin Atkinson in a 2003 paper using computational methods on Swadesh lists have arrived at a somewhat earlier estimate, around 5000 BC for Greco-Armenian split and the emergence of Greek as a separate linguistic lineage around 4000 BC.

...
Wikipedia