as you seen in troy movie,greece was not like our modern nations.it was more likely a loose unioun of independent states;like athica,arcadia etc.but they have some common features like greek language,culture.once any state got power.it controlled other state, as u seen in troy agmennon controled the other state-kings.
in these maps u can see the states of ancient greece. u can compare tese locations with modern greece map for better understanding.