Ancient Greece was made up of many city-states which were ruled in different ways. Some were ruled by groups of rich and influential people. Sparta had two kings and a small group of elders. Athens had a democratic system of government, voted for by the people, which prevented anyone getting too much power. None of the states allowed women, foreigners or slaves to take part in government.
In the fourth century BC Alexander the Great became overall ruler of the city-states of Greece.