century and the beginning of the 9th century that an Afrighid Shah first converted to Islam appearing with the popular convert's name of ʿAbdullah ('slave of God'). In the course of the 10th century—when some geographers such as Istakhri in his Al-Masalik wa-l-mamalik mention Khwarezm as part of Khorasan and Transoxiania—the local Ma'munids, based in Gurganj on the left bank of the Amu Darya, grew in economic and political importance due to trade caravans. In 995, they violently overthrew the Afrighids and themselves assumed the traditional title of Khwarazm-Shah. Briefly, the area was under Samanid suzerainty, before it passed to Mahmud of Ghazni in 1017. From then on, Turko-Mongolian invasions and long rule by Turko-Mongol dynasties supplanted the Iranian character of the region although the title of Khwarezm-Shah was maintained well up to the 13th century. Khwarezmid Empire The date of the founding of the Khwarazmian dynasty remains debatable. During a revolt in 1017, Khwarezmian rebels murdered Abu'l-Abbas Ma'mun and his wife, Hurra-ji, sister of the Ghaznavid sultan Mahmud. In response, Mahmud invaded and occupied the region of Khwarezm, which included Nasa and the ribat of Farawa. As a result, Khwarezm became a province of the Ghaznavid Empire from 1017 to 1034. In 1077, the governorship of the province, which since 1042/1043 belonged to the Seljuqs, fell into the hands of Anush Tigin Gharchai, a former Turkic slave of the Seljuq sultan. In 1141, the Seljuq Sultan Ahmed Sanjar was defeated by the Qara Khitai at the battle of Qatwan, and Anush Tigin's grandson Ala ad-Din Atsiz became a vassal to Yelü Dashi of the Qara Khitan. Sultan Ahmed Sanjar died in 1156. As the Seljuk state fell into chaos, the Khwarezm-Shahs expanded their territories southward. In 1194, the last Sultan of the Great Seljuq Empire, Toghrul III, was defeated and killed by the Khwarezm ruler Ala ad-Din Tekish, who conquered parts of Khorasan and western Iran. In 1200, Tekish died and was succeeded by his son, Ala ad-Din Muhammad, who initiated a conflict with the Ghurids and was defeated by them at Amu Darya (1204). Following the sack of Khwarizm, Muhammad appealed for aid from his suzerain, the Qara Khitai who sent him an army. With this reinforcement, Muhammad won a victory over the Ghorids at Hezarasp (1204) and forced them out of Khwarizm. Mongol conquest by Genghis Khan The Khwarezmid Empire ruled over all of Persia in the