1) Historical era 
Pentecontaetia (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 433 BC. The term originated with Thucydides, who used it in his description of t.....