Hadean
The Hadean () is a geologic eon of the Earth pre-dating the Archean. It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the ICS, 4 billion years ago. , the ICS describes its status as ""informal"". Geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term, the "Priscoan period", from "priscus", the Latin word for "ancient". Other, older texts simply refer to the eon as the Pre-Archean.
Hellenistic Greece
The Hellenistic period began with the wars of the Diadochi, armed contests among the former generals of Alexander the Great to carve up his empire in Europe, Asia, and North Africa. The wars lasted until 275 BC, witnessing the fall of both the Argead and Antipatrid dynasties of Macedonia in favor of the Antigonid dynasty. The era was also marked by successive wars between the Kingdom of Macedonia and its allies against the Aetolian League, Achaean League, and the city-state of Sparta.