 Many experts such as Sir Percy Sykes in fact called the Elamites "the earliest civilization of Persia" ("A History of Persia", p38), and Ibn Nadeem in his book "al-Fehrest" ("الفهرست"), mentions that all the Median and Persian lands of antiquity spoke one language.In his book, which is the most accredited account of spoken languages of Iran during the early Islamic era, Ibn Nadeem quotes the 8th century scholar Abdullah Ibn al-Muqaffa as having counted "Khuzi" among the Iranian languages and for having identified it as the unofficial language of the royalty of Iran.In 644 BCE, the Assyrian king Ashurbanipal conquered Elam and destroyed their capital at Susa.