They developed a philosophical approach to history, asking questions about the causes of events and the role of individuals in history
They wrote some of the earliest surviving historical works, such as Herodotus's "Histories" and Thucydides's "History of the Peloponnesian War"
They established a tradition of historiography, which is the study of how history is written and interpreted
They developed the concept of periodization, which is the division of history into different time periods