Ruler of the Khwarazmian Empire
Jalal al-Din Mangburni (Persian: جلال الدین مِنکُبِرنی), also known as Jalal al-Din Khwarazmshah (جلال الدین خوارزمشاه), was the last Khwarazmshah of the Anushteginid dynasty. The eldest son and successor of Ala ad-Din Muhammad II of the Khwarazmian Empire, Jalal al-Din was brought up at Gurganj, the wealthy capital of the Khwarazmid homeland. An able general, he served as second-in-command to his father in at least one battle; however, since he was the son of a concubine, he was challenged as successor by a younger brother, whose cause was supported by the powerful Queen Mother, Terken Khatun. Nevertheless, after the Mongol conquest of the Khwarazmian Empire led to his father's flight and death on an island in the Caspian Sea, Jalal-al Din gained the loyalty of the majority of Khwarazmian loyalists.
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“Beyond any doubts, Allah punished Jalal ad-Din for his sins and granted no respite to him but rooted him out. Still, his death marked the extermination of Muslims by the Mongols. After the death of his father ‘Ala ad-Din Muhammad, after the destruction of the countries by the Mongols and the carnages over the population Jalal ad-Din fled to India, then turned back. His might increased, his position consolidated, so he captured Kerman, Persian Iraq, Azerbaijan and Arran, and he had an enormous army. If he had behaved decently and justly, if he had not shed no blood, he could have fought the Mongols properly and his army could have been a buffer between us and the Mongols. However, he led a vicious life, sinned, made injustices, was at loggerheads with his neighbours, behaved treacherously and caused displeasure. That led to his death and to the ruin of his army. Next came the Mongolian invasion and the Mongol’s triumph over the countries of Islam. If Allah wishes something, He brings about its causes”. - Ibn Wasil.
"Jalâl al-Dîn was a bad ruler who administered his realm abominably. Among the rulers who were his neighbours he did not leave one without showing hostility to him and challenging him for his kingdom, acting as a bad neighbour. As an example of that, as soon as he appeared in Isfahan and gathered an army, he invaded Khuzistan and besieged Tustar, a possession of the caliph. He marched to Daquqa, which he sacked and where he killed many people. It too belonged to the caliph. Then he took Azerbayjan, which was held by Uzbek, and attacked the Georgians, whom he defeated and harassed. Later he made war on al-Ashraf, lord of Khilât, and then on ‘Alâ’ al-Dîn, ruler of Anatolia, and on the Ismâ‘îlîs, whose lands he ravaged and many of whom he killed. He imposed upon them an annual tribute in money and also on others. Every ruler abandoned him and would not take his hand." - Ibn Al Athir.