I have always thought proto-celts or some other northern/east asian peoples. I have also wondered just what the heck happened to the bronze age Greeks? Did not Greece go thru it's own a dark age 1500BC - 800BC? Wonder why?
Probably the usual reasons - invasions coupled with famines.
Interestingly, Lithuanian has a number of striking similarities to both Ionian Greek and Sanskrit.
Of the European languages, Lithuanian may be the closest to proto-Indoeuropean.
The northern people moved south because it got 'real' cold in the north and they were starving. All the 'Dark Ages' were worldwide events as recorded in the tree-rings. Read the article below for some insight on the subject.
The Dark Ages: Were They Darker Than We Imagined?
"The twelfth century BC is associated with the "Greek Dark Ages", the end of the Hittite civilisation in the Near East, the end of Bronze Age Israel, and the end of the Bronze Age Shang dynasty in China. Ancient Chinese history has the notion of "mandate from heaven", where the rulers were essentially subject to the whims of the sky above. Strange sights in the sky would not be seen as good news for Chinese Emperors. Indeed, around this time, Chinese records speak of : "
Spartans and Pelloponesians generally were from northern Dorians and worshipped Apollo ('Phoebus'), like the Trojans.
Athenians were from Ionians, favorites of `grey-eyed' Athena Palla and believed themselves to be the `original' Greeks.
Helen of Sparta was hatched from a egg, so maybe that was why she was such a hot chick. Spartan women had a reputation for beauty, could have sex with their husband's friends, were said by Aristotle to rule their men and were called "thigh-flashers" by other Greeks.
The supposed Dark Age of Greece is illusory. It's important to note I think that while there is some Linear B material (archaic Greek) from Pylos (excavated by Carl Blegen) and some other mainland sites, probably other written material (perhaps on non-durable items like papyrus or parchment) was destroyed with the palaces. Pollen cores show that the period of the supposed Dark Age saw some of the heaviest (ever) cultivation of olive trees. :')