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
After Alexander the Great's invasion of the Achaemenid Empire in 330 BC and its disintegration shortly after, the Hellenistic kingdoms were established throughout south-west Asia (Seleucid Empire, Kingdom of Pergamon), north-east Africa (Ptolemaic Kingdom) and South Asia (Greco-Bactrian Kingdom, Indo-Greek Kingdom). The Hellenistic period was characterized by a new wave of Greek colonization which established Greek cities and kingdoms in Asia and Africa. This resulted in the export of Greek culture and language to these new realms, spanning as far as modern-day India. Equally, however, these new kingdoms were influenced by the indigenous cultures, adopting local practices where beneficial, necessary, or convenient. Hellenistic culture thus represents a fusion of the Ancient Greek world with that of the Near East, Middle East, and Southwest Asia. This mixture gave rise to a common Attic-based Greek dialect, known as Koine Greek, which became the "lingua franca" through the Hellenistic world.