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.
The Hyborian Age
The essay sets out in detail the major events of Howard's pseudohistorical prehistory, both period before and after the time of the Conan stories. In describing the cataclysmic end of the Thurian Age, the period described in his Kull stories, Howard links both sequences of stories into one shared universe. The names he gives his various nations and peoples of the age borrow liberally from actual history and myth. The essay also sets out the racial and geographical heritage of these fictional entities, making them progenitors of modern nations. For example, Howard makes the Gaels descendants of his own Cimmerians.