It is true that Ancient Greek was shaped by both isolation and intercultural exchange:
Isolation was due to the geographical conditions of Greece, it was divided by mountains, rivers and forests forming independent cities instead of a central monarchy. The fact helped every city progress in their own unique way and brought out a variety of cultural and intellectual possibilities.
Intercultural exchanges were due to the presence of sea which allowed them to trade with different cultures like Persian, Frankish states, Ottoman Empire, Genoese Republic and British Empire. All of these in their various ways left their influence on modern Greek culture.