There was not one country called "Ancient Greece." Instead, there were small ' city-states'. Each city-state had its own goverment. Sometime the city-states fought one another, sometimes they joined together against a bigger enemy, the Persian And Empire. Athens, Sparta, Corinth and Olympia were four of these city-states. Only a very powerful ruler could control all Greece. One man did in the 300s BC. He was Alexander the Greatm, from Macedonia. Alexander led his army to conquer not just Greece but an empire that reached as far as Afghanistan and India.