Answer:
Democracy.
Step-by-step explanation:
In the period of Ancient Greece there were many city-states established, that had different forms of government. The most peculiar one was created in Athens, known to us as democracy. With many reforms introduced by Cleisthenes, Solon and others, Athenians created a system inside which the people had authority and possibility to govern themselves through certain institutions such as Ecclesia. Of course, Athenian democracy differed from modern democracy as a lot of people didn't had the right to participate in public life.