[Grimmy]

This ain’t me doing my usual snark but asking a question for realzies.

Didn’t the ancient Greeks write about a people in that area that was there before them? The Pelasgis (or however it’s spelled)?

I recall reading something about how the Greeks credited them with teaching how to build large stone walls and such.

[SunkenCiv]

Herodotus credits the Phoenicians with the introduction of alphabetic writing. Prior to that, the use of Linear B (Greek), Linear A (non-Greek, probably Carian or related language), and perhaps even cuneiform (the writing system used for international diplomatic and possibly commercial communication for thousands of years) was around for a long period.

The Pelasgians are referred to in ancient writing, but there’s no clear idea who they were. I’m not one to say they never existed, it seems likely that they were an earlier coat of paint — or more than one — and probably also Indo-European speakers.

[Verginius Rufus]

There are various mentions in Greek sources of the Pelasgians but they are rather mysterious. One scholar tried to equate them with the Philistines but I don't think anyone else agreed with him. Their language may be related to Etruscan. The island of Lemnos had a non-Greek-speaking population until fairly late when it was conquered by the Athenians and a couple of inscriptions have been found there in a language similar to Etruscan (but written in the Greek alphabet).

A lot of place names in Greece are pre-Greek: Athens, Corinth, Knossos, Parnassos, etc. There are also many loan words in Greek which seem to come from the same language. One of them is plinthos, "brick," which may indicate that the Greeks learned how to build with bricks from the earlier population.