At the same time, Sultan Mehmet had escaped from the war. He did not know where his son was. The Mongols were pursuing Mehmet. Genghis Khan had issued the following order to his three commanders he sent to pursue: Go without stopping. Forgive those accepting your dominance, kill those who do not, take their children captive.
Destroy castles! Do this in three years! I am turning back to my country...
Sultan Mehmet went to Harandar castle with a few of his men and left his family and treasure there. He started to escape toward Iraq. However, he came across Mongols on his way. Although his horse was killed with an arrow, he was able to escape. At last, he reached Kuzgun sea. He took shelter in Aboskon Island there.
Mongols, on the other hand, sent the vizier, little son of Sultan Mehmet and Turkan Hatun to Genghis. Genghis killed all of them. Sultan Alaeddin felt faint and fell down. He was so miserable that his friends could not even find a shroud to wrap around his body. They turned the shirt of Mahmut Çavuş, one of his men, into his shroud. He had said I am the owner of all these territories. But now I cannot find two meters of soil to dig my grave!, before his death.
While Sultan Mehmet passed away in poverty, his son Celaleddin Harzemşah was with him. He had seen the bad aspects of life. However, in his heart, he felt a deep desire to take revenge against the crowds of people from east. What could Celaleddin do against these forces forcing Turk out of his country? He was thinking about this when he left his fathers grave in tears. He had about 70 horsemen with him. He went to Harzem directly.
The people welcomed him in tears of joy. The dissolved army was put in order again. 7.000 people gathered under command of Harzemşah. Celaleddin substituted his father. After a period of time, he assaulted on the Mongols and defeated them.
Mongols took the offensive at the moment that he surrounded Valyan Fortress in 1221. Celaleddin Harzemşah took the lead with his unsheathed sword and perturbed the enemy. However, Mongols made mannequins of shawl and felt at midnight on their horses. They aligned these behind them. Harzemliler wanted to escape thinking that Mongols took help. Celaleddin said Do not be afraid, this is a trick. They always win wars with such tricks... and prevented defeat. Therefore, Mongol armies were defeated once more.
When Genghis was informed of this, he marched toward Celaleddin in person. However, Celaleddin, upon seeing so great forces marching toward him, began to escape toward Sind river. He wanted to cross this river. However, Mongols surrounded Celaleddin with soldiers four times more than that of Celaleddin. Hero Celaleddin was left between fire and water. What could he do at that moment? Genghis had ordered that he should be caught alive. Genghis unsheathed his sword and began to fight against soldiers wanting to take him captive. No enemy soldiers shot arrows. The chamber surrounded him was narrowed slowly. Celaleddin attacked but could not split that chamber. He had only one thing to do: He got on a horse which was not tired and put his shield back and handed Turkish flag and threw himself from a high cliff to the violent waters of Sind river. He crossed the river, swimming.
Genghis and his soldiers watched this scene of heroism in surprise and admiration. Sultan Celaleddin started to work to gather his state again turning back to Kirman in 1224 three years later. He captured Tabriz in 1225 and carried his headquarters there, and fought a war against Mongol army in Isfahan in 1228. Despite betrayal of his brother Gıyaseddin, he defeated the Mongols, and he escaped to Luriston because the left wing of the army fell in a trap.
Celaleddin, dealing with rebellions in the country at the same time, seized Ahlat in 1230. However, his violent behavior against those defending the fortress and the people attracted enmity on the side of neighboring Muslim countries. Thereupon, Anatolian and Syrian forces merged and attacked on Celaleddin. Celaleddin routed in the Yassıçimen plateau near Erzincan on 10 August 1230.
Mongols, availing from weakening of Celaleddin took the offensive again. Other Muslim countries, not being capable of perceiving Mongol danger, did not answer the help demand of Celaleddin. All men of Celaleddin were killed on whom Mongols raided near a bridge on Tigris. Celaleddin Harzemşah who escaped and withdrew to the mountains was killed by nomads there.