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.
Hadendoa
The southern Beja were part of the Christian kingdom of Axum during the sixth to fourteenth centuries.
In the fifteenth century, Axum fell to the Islamization of the Sudan region, and although the Beja were never entirely subjugated, they were absorbed into Islam via marriages and trade contracts. In the seventeenth century, some of the Beja expanded southward, conquering better pastures. These became the Hadendoa, who by the eighteenth century were the dominant people of eastern Sudan, and always at war with the Bisharin tribe.