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.
Mycenaean Greece
The Late Helladic period is further divided into LHI and LHII, both of which coincide with the early period of Mycenaean Greece (c. 1650–1425 BC), and LHIII (c. 1425–1050 BC), the period of expansion, decline and collapse of the Mycenaean civilization. The transition period from the Bronze Age to the Iron Age in Greece is known as Sub-Mycenaean (c. 1050–1000 BC).