stylistic:tone, information:filtering, linguistic:paraphrasing
Language

Religious diversity notwithstanding, the spread of Arabic as the main language of the population had already progressed rapidly before the Fatimid period. In parts of Egypt, Copts and possibly also some Muslim communities were still speaking Coptic when the Fatimids arrived on the scene. It is during the Fatimid period, however, that Coptic religious culture began to be translated into Arabic. By the end of the Fatimid period (12th century), many Coptic Christians could no longer understand the Coptic language, and eventually its usage was reduced to a liturgical language.