During Sultan Qutb-ud-din Aibak’s time, the Mongols, appeared in the East of India and emerged as a great power under the leadership of Genghiz Khan (1165-1227). He was born in 1165 to Yesugei and Hoelun. He was brought up by his ablest mother Hoelun after his father was poisoned to death by Tatars. In his incessant wars, he exhibited such remarkable traits of heroism and diplomacy that led him to transform the entire social and military structure of Mongolia.
The Mongol troops had a strict code of discipline and harsh penalties for infringements of regulations. The Mongol
hordes were divided in units of 10, 100, 1,000, and 10,000 soldiers (known as an arban, jagun, minghan and tümen respectively; the latter corresponds to a modern regiment).
Under this system fighters from different tribes were united in unified military formations, whose chief strategy was to “march divided, attack united,” and the strategies used were based on large-scale skirmish manoeuvres that helped the Mongols defeat numerically superior but fragmented forces from the Oxus to the Volga.
While chasing Jalal-ud-Din Khwarzam Shah (Ruler of Khwarazmian dynasty), Genghiz Khan stormed Afghanistan and the territories nowadays parts of Pakistan. Initially, Jalal-ud-Din defeated an advance Mongol army with the help of the Afghan fighters. However after the coming of Genghiz Khan, Jalal-ud-Din left Ghazni and entered into the areas of the Delhi Sultanate and encamped at the west bank of river Indus. In December 1221 AD, Genghiz Khan followed him and crushed his army while he fled crossing the Indus waters. He was given refuge by the Delhi Sultan. Genghiz Khan marched back due to hot summer. But in his way back he devastated the present day Punjab, Afghan borderland, Ghazni and Herat.
In 1235 Mongol force invaded Kashmir, stationing a darughachi (administrative governor) there for several years, and Kashmir became a Mongolian dependency
In 1285 AD, the Mongols invaded Multan and killed Prince Muhammad Khan.
During the reign of Ala-ud-din Khilji, Mongols invaded the country several times but were successfully repulsed. From these invasion Alla-ud-din Khilji learnt the lessons of keeping himself prepared, by fortifying and organizing his armed forces.
The invasion of Mongol ruler Timur in 1398 A.D. sealed the fate of the Tughluq dynasty. Muhammad fled and Timur captured the city and destroyed many temples in north India. Thousands of people were killed and Delhi was plundered for fifteen days, Timur returned to Samarkhand carrying away a large amount of wealth with him.