Sorry if my word choice is poor but as I understand Greece is a very new country with a VERY turbulent recent history. But after the original Greece existed and after the Romans / Byzantines (so Romans) then Ottomans inhabited the modern day land of Greece for millennia has the idea of 'Greece' existed for all this time? Or is it a new construct used to foster nationalism and power.
https://www.reddit.com/r/AskHistorians/comments/1a4h57/how_did_greek_identity_change/
This comment talks a bit about it
Edit:
https://www.reddit.com/r/AskHistorians/comments/19ui3r/how_exactly_did_greeks_call_themselves_greek/
Talks about how ancient greeks saw and how they identified themselves