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.
Golden age of Jewish culture in Spain
The nature and length of this "Golden Age" has been debated, as there were at least three periods during which non-Muslims were oppressed. A few scholars give the start of the Golden Age as 711–718, the Muslim conquest of Iberia. Others date it from 912, during the rule of Abd-ar-Rahman III. The end of the age is variously given as 1031, when the Caliphate of Cordoba ended; 1066, the date of the Granada massacre; 1090, when the Almoravids invaded; or the mid-12th century, when the Almohads invaded.