Greece emerged from its 'Dark Ages' as a series of independent city-states which constantly fought with each other. In the early 5th century BC, however, these city-states had to band together against invasions from Persia in the east.
After their victory, the Greeks entered their 'Golden Age'. Initially there was a great sense of Panhellenism (All-Greek unity) with religion in particular being a source of solidarity.
This soon gave way to rationalism and individualism in inter-state relations and also within the city-states themselves. The result of this was a great surge in intellectual activity and outstanding artistic achievement. These were the hallmarks of the 'Classical' era.
In the course of the late 5th and 4th centuries, however, old feuds and conflicts reopened and the Greeks ruined themselves through internal warfare.
Athens, Sparta, and Thebes in turn attempted to win hegemony(leadership and pre-eminence) over the Greek World, but all failed. Finally, the Greeks succumbed to the Macedonians under King Philip II and Alexander the Great between 352 and 335 BC.
