The Afrighids (Khwarazmian: ʾfryḡ) were a native Khwarezmian Iranian dynasty who ruled over the ancient kingdom of Khwarezm. Over time, they were under the suzerainty of the Sasanian Empire, the Hephthalite Empire, the Göktürk Khaganate, the Umayyad Caliphate, Abbasid Caliphate and the Samanid Empire. They were ultimately deposed by a rival family, the Ma'munids of Gurganj, who became the new rulers of Khwarazm. Al-Biruni, the native Khwarezmian scholar, mentions twenty-two members of the Afrighid dynasty for a total span of 690 years with an average rule of 31 years for each ruler. According to him, the Afrighids ruled from 305, through the Arab conquests under Qutayba ibn Muslim in 712, and up to their overthrow in 995 by the rising rival family of Ma'munids. The main source on the Afrighids prior to Islam is also Al-Biruni. Part of the reason for the gap in information about this dynasty is mentioned by Al-Biruni. Al-Biruni states: When Qutaibah bin Moslem under the command of Al-Ḥajjāj ibn Yūsuf was sent to Khwarazmia with a military expedition and conquered it for the second time, he swiftly killed whoever wrote in the Khwarazmian native language and knew of the Khwarazmian heritage, history, and culture. He then killed all their Zoroastrian priests and burned and wasted their books, until gradually the illiterate only remained, who knew nothing of writing, and hence the region's history was mostly forgotten. It has been suggested that 'Afrigh' is the Arabicized of 'Abriz' in Persian (آبریز where water flows, a reference to the geography of Khwarazm and its abundant water). However, Dr. Parviz Azkai, in his annotations on Al-Biruni's Chronology of Ancient Nations, explains that this is a popular etymology. Azkai explains that Afrigh was originally Ap-Air-ig meaning from the Aryan descent: ap or af is the same in 'afrashtan' (Persian: افراشتن) to raise; air is the root meaning Aryan as seen in Iraj, and Eran/Iran (land of Aryan); and -ig is the suffix of relation in Iranian languages and cognate to '-ic' in English or '-ique' in French.