Muhammad II of Khwarezm

Ala ad-Din Muhammad II (علاءالدين محمد ʿAlā al-Dīn Muḥammad) was the ruler of the Khwarezmid Empire from 1200 to 1220. His father was a Turkic slave who eventually became a viceroy of a small province named Khwarizm. After his father died, Muhammad inherited his father's lands, and it was from there he began expanding outwards. By 1205 he had conquered all of Persia from the Seljuk Turks and in 1212 he defeated Kutluk, the Gur-Khan of the Kara Khitay (Kara-Khitan Khanate). When he had conquered all the lands from the river Jaxartes to the Persian Gulf he declared himself shah and demanded formal recognition from the caliph in Baghdad. When the caliph an-Nasir rejected his claim, Ala ad-Din Muhammad proclaimed one of his nobles caliph and marched towards Baghdad to depose an-Nasir. However, when crossing the Zagros Mountains, the shah's army was caught in a blizzard. Thousands of warriors died and with the army decimated the generals had no choice but to return home.

It was in this situation that, in 1218, Genghis Khan sent his emissaries to the shah in Samarkand. The shah executed the Mongol diplomats and sent back their entourage with their heads shaved in defiance of the emerging great power, and Genghis retaliated with a force of 200,000 men that crossed the Jaxartes in 1220 and sacked the cities of Samarkand and Bukhara. Muhammad's capital, Urgench, followed in 1221. Ala ad-Din Muhammad fled and sought refuge throughout Khorasan, but died of pleurisy on an island in the Caspian Sea near the port of Abaskun some weeks later.

References

Neil Blandford & Bruce Jones - The World's Most Evil Men, 1985
Nigel Cawthorne - The World's Worst Atrocities, 1999