Pentecontaetia
Pentecontaetia (Greek: πεντηκονταετία, "the period of fifty years") is the term used to refer to the period in Ancient Greek history between the defeat of the second Persian invasion of Greece at Plataea in 479 BC and the beginning of the Peloponnesian War in 431 BC. The term originated with a scholiast commenting on Thucydides, who used it in their description of the period. The Pentecontaetia was marked by the rise of Athens as the dominant state in the Greek world and by the rise of Athenian democracy, a period also known as Golden Age of Athens.