The Mongol armies split up and rampaged through central and western Persia Afghanistan and northwest India. Only one valiant prince, Jalaluddin, had the backbone to stand up to the marauding invaders. Jalaluddin, the third son of the Shah, fought the Mongols at every turn and on one occasion in 1220, inflicted a defeat upon a Mongol division in Afghanistan. Pressed further by the Mongols, the Prince retreated eastward and took a stand by the Indus River near Attock. With the great river to his back and a high ridge to his left, Jalaluddin charged like a lion towards the Mongol center where Genghiz Khan was stationed.

He succeeded in reaching the spot. But man plans and God disposes. Despite the most well thought-out human plans, the outcome of great wars is a moment of Divine intercession. As providence would have it, Genghiz had dismounted his horse at that moment and had gone off to attend to other matters. Genghiz escaped and the wheels of history turned. Jalaluddin’s bodyguard was cut to pieces. Desperate, the undaunted prince plunged his horse from a ridge into the Indus and as he swam the great river towards Hindustan, Genghiz is said to have exclaimed: “Proud should be a mother who bore such a son!”

By 1222, when Genghiz finally retreated towards Mongolia, he had destroyed what are today the states of Kazakhstan, Uzbekistan, Kyrigistan, Turkmenistan, Tadzighistan, Persia, Afghanistan and western Pakistan. The great cities of Samarqand, Bukhara, Merv, Herat, Ghazna, Kabul and Neshapur were razed to the ground. In the words of Ibn Kathir, not even one hundredth of the population of the area survived. This was only the beginning. After the death of Genghiz Khan, the Mongols continued their advance into west Asia and central Europe, destroying whatever lay before them and reshaping the destinies of Asia and Europe alike.

 Thus it was that in the first two decades of the 13th century, the opening gambit of the great geopolitical game between the worlds of Islam, Medieval Christianity and the Mongols was played and the stage was set for the global struggles that were to follow in the latter part of the century.

source:

https://historyofislam.com/contents/the-post-mongol-period/genghiz-khan/

http://97.105.52.213/en/artical/21414/Mongol-armies-rampage