The advent of the Khalji dynasty marked the zenith of Muslim imperialism in India. The founder of the Khalji dynasty was Jalaluddin Khalji. He was seventy years old when he came to power. He was generous and lenient. Malik Chhajju, nephew of Balban was allowed to remain the governor of Kara. His leniency was misunderstood as weakness. When Chhajju revolted, it was suppressed but he was pardoned. When the thugs (robbers) looted the country, they were allowed to go after a severe warning. In 1292 when Malik Chhajju revolted for the second time, he was replaced by his son-in-law, Alauddin Khalji. In 1296 Alauddin Khalji took an expedition to Devagiri and returned to Kara. During the reception there, Alauddin Khalji treacherously murdered his father-in-law Jalaluddin Khalji and usurped the throne of Delhi.
Alauddin Khalji made enormous gifts to the hostile nobles and Amirs of Delhi to win over them to his side. Those who still opposed him accession were punished severely. He framed regulations to control the nobles. He was convinced that the general prosperity of the nobles, inter-marriages between noble families, inefficient spy-system and drinking liquor were the basic reasons for the rebellions. Therefore, he passed four ordinances. He confiscated the properties of the nobles. The intelligence system was reorganized and all the secret activities of the nobles were immediately reported to the Sultan. The public sale of liquor and drugs was totally stopped. Social gatherings and festivities without the permission of Sultan were forbidden. By such harsh measures his reign was free from rebellions.
Alauddin Khalji maintained a large permanent standing army and paid them in cash from the royal treasury. According the Ferishta, he recruited 4,75,000 cavalrymen. He introduced the system of dagh (branding of horses) and prepared huliya (descriptive list of soldiers). In order to ensure maximum efficiency, a strict review of army from time to time was carried out.
The introduction of paying salaries in cash to the soldiers led to price regulations popularly called as Market Reforms. Alauddin Khalji established four separate markets in Delhi, one for grain; another for cloth, sugar, dried fruits, butter and oil; a third for horses, slaves and cattle; and a fourth for miscellaneous commodities. Each market was under the control of a high officer called Shahna-i-Mandi. The supply of grain was ensured by holding stocks in government store-houses. Regulations were issued to fix the price of all commodities. A separate department called Diwani Riyasat was created under an officer called Naib-i-Riyasat. Every merchant was registered under the Market department. There were secret agents called munhiyans who sent reports to the Sultan regarding the functioning of these markets. The Sultan also sent slave boys to buy various commodities to check prices. Violation of regulations was severely punished. Harsh punishment was given if any shop-keeper charged a higher price, or tried to cheat by using false weights and measures. Even during the famine the same price was maintained. We are not sure whether the market regulations in Delhi were also applied in the provincial capitals and towns.
Apart from market reforms, Alauddin Khalji took important steps in the land revenue administration. He was the first Sultan of Delhi who ordered for the measurement of land. Even the big landlords could not escape from paying land tax. Land revenue was collected in cash in order to enable the Sultan to pay the soldiers in cash. His land revenue reforms provided a basis for the future reforms of Sher Shah and Akbar.
Alauddin Khalji sent his army six times against the Mongols. The first two was successful. But the third Mongol invader Khwaja came up to Delhi but they were prevented from entering into the capital city.
The next three Mongol invasions were also dealt with severely. Thousands of Mongols were killed. The northwestern frontier was fortified and Gazi Malik was appointed to as the Warden of Marches to protect the frontier. The military conquests of Alauddin Khalji include his expedition against Gujarat, Mewar and the Deccan. He sent Nusrat Khan and Ulugh Khan to capture Gujarat in 1299. The king and his daughter escaped while the queen was caught and sent to Delhi. Kafur, an eunuch, was also taken to Delhi and later he was made the Malik Naib - military commander. Then in 1301, Alauddin marched against Ranthampur and after a three month's siege it fell. The Rajput women committed jauhar or self-immolation.
Alauddin next turned against Chittor. It was the powerful state in Rajasthan. The siege lasted for several months. In 1303 Alauddin stormed the Chittor fort. Raja Ratan Singh and his soldiers fought valiantly but submitted. The Rajput women including Rani Padmini performed jauhar. This Padmini episode was graphically mentioned in the book Padmavath written by Jayasi.
Alauddin Khalji's greatest achievement was the conquest of Deccan and the far south. This region was ruled by four important dynasties - Yadavas of Devagiri, Kakatiyas of Warangal, Hoysalas of Dwarasamudra and the Pandyas of Madurai. In Alauddin sent Malik Kafur against the ruler of Devagiri, Ramachandra Deva, who submitted and paid rich tributes. In 1309 Malik Kafur launched his campaign against Warangal. Its ruler Pratabarudra Deva was defeated and enormous booty was collected from him. Malik Kafur's next target was the
Hoysala ruler Vira Ballala III. He was defeated and a vast quantity of booty was seized and sent to Delhi. Kafur next marched against the Pandyas. Vira Pandya fled the capital Madurai and Kafur seized enormous wealth from the Pandya kingdom and returned to Delhi.
Alauddin Khalji died in 1316. Although the Sultan was illiterate, he patronized poets like Amir Khusrau and Amir Hasan. He also built a famous gateway known as Alai Darwaza and constructed a new capital at Siri.
Mubarak Shah and Khusru Shah were the successors of Alauddin Khalji. Ghazi Malik, the governor of Dipalpur, killed the Sultan Khusru Shah and ascended the throne of Delhi under the title of Ghiyasuddin Tughlaq in 1320.