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.
Helladic chronology
In Greece, the Middle Helladic period (or MH) was a period of cultural retrogression, which first manifested in the preceding EHIII period. The MH period is characterized by the wide-scale emergence of Minyan ware, which may be directly related to the people whom ancient Greek historians called Minyans; a group of monochrome burnished pottery from Middle Helladic sites was conventionally dubbed "Minyan" ware by Troy's discoverer Heinrich Schliemann.