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 period
During the reign of Mithridates I of Parthia, Arsacid control expanded to include Herat (in 167 BC), Babylonia (in 144 BC), Media (in 141 BC), Persia (in 139 BC), and large parts of Syria (in the 110s BC). The Seleucid–Parthian wars continued as the Seleucids invaded Mesopotamia under Antiochus VII Sidetes (r. 138–129 BC), but he was eventually killed by a Parthian counterattack. After the fall of the Seleucid dynasty, the Parthians fought frequently against neighbouring Rome in the Roman–Parthian Wars (66 BC – 217 AD). Abundant traces of Hellenism continued under the Parthian empire. The Parthians used Greek as well as their own Parthian language (though lesser than Greek) as languages of administration and also used Greek drachmas as coinage. They enjoyed Greek theater, and Greek art influenced Parthian art. The Parthians continued worshipping Greek gods syncretized together with Iranian deities. Their rulers established ruler cults in the manner of Hellenistic kings and often used Hellenistic royal epithets.