Complex sentence: The ruins of Gordion and Midas City prove that Phrygia had developed an advanced Bronze Age culture and that Phrygian and Greek cultures interacted in a number of ways in various periods of history.
Split into simpler sentences: The ruins of Gordion and Midas City prove that Phrygia had developed an advanced Bronze Age culture. This Phrygian culture interacted in a number of ways with Greek culture in various periods of history.