There is no question whatsoever that the Arabs did indeed destroy much of the heritage of Classical civilization, including many - or even the great majority - of the works of the ancient authors. This is proved beyond doubt by the rapid severing of links with the past which followed the Muslim conquest. Within a very short time indeed no one in Egypt had any idea of the name of the pharaoh who built the Great Pyramid - though this knowledge had earlier been readily available in the works of Greek writers such as Herodotus and Diodorus, as well as native Egyptian writers working in Greek, such as Manetho. And the same severing of links with the past is found throughout the Muslim world. By the eleventh century the Persian poet and mathematician Omar Khayyam could not name the builders of the great palaces at Persepolis and Susa. These structures, he imagined, had been raised by a genie-king named Jamshid.