Khwarazmian dynasty
The Khwarazmian dynasty only lasted for a few decades, until the arrival of the Mongols. Genghis Khan had unified the Mongols, and under him the Mongol Empire quickly expanded in several directions. In 1218, it bordered Khwarezm. At that time, the Khwarazmian Empire was ruled by Ala ad-Din Muhammad (1200–1220). Muhammad, like Genghis, was intent on expanding his lands and had gained the submission of most of Iran. He declared himself shah and demanded formal recognition from the Abbasid caliph Al-Nasir. When the caliph rejected his claim, Ala ad-Din Muhammad proclaimed one of his nobles caliph and unsuccessfully tried to depose an-Nasir.