Alauddin Khalji was Jalaluddin’s nephew and son-in-law.
Alauddin had two victorious expeditions during the reign of Jalaluddin.
After the first expedition of Bhilsa (Vidisa) in AD 1292, he was given the iqta of Awadh, in addition to that of Kara.
He was also appointed Arizi-i-Mumalik (Minister of War).
In AD 1294, he led the first Turkish expedition to southern India and plundered Devagiri.
In July AD 1296, he murdered his uncle and father-in-law Jalaluddin Khalji and crowned himself as the Sultan.
Alauddin decided to revive Balban’s policies of ruthless governance. He decided to curb the powers of the nobles and interference of Ulema in the matters of the state.
In order to prevent the re-occurrence of these rebellions, Alauddin formulated certain regulations and implemented them.
(1) Families that had been enjoying free land to support themselves should pay land tax for their holdings. This curbed the excess of wealth owned by some people.
(2) The Sultan reorganized the spy system and took measure to make it more effective.
(3) The use of liquor and intoxicants was prohibited.
(4) The nobles were ordered not to have social gatherings or inter-marriages without his permission.
Market Regulations of Alauddin Khalji
To control the prices, Alauddin set up three different markets for different commodities in Delhi.
These markets were
 the grain market (Mandi),
 cloth market (Sarai Adl) and
 the market for horses, slaves, cattles, etc.
To ensure implementation, Alauddin appointed a superintendent (Shahna-i-Mandi) who was assisted by an intelligence officer.
Apart from Shahna-i-Mandi, Alauddin received daily reports of the market from two other independent sources, barid (intelligence officer) and munhiyans (secret spies).
Control of prices of horses was very important for the Sultan because without the supply of good horses at reasonable price to army, the efficiency of the army could not be ensured.
Low price in the horse market were ensured by putting a stop to the purchase of horses by horse dealers and brokers (dalals) in Delhi market.
Expansion of Delhi Sultanate
Under Alauddin Khalji the territorial expansion of the Delhi Sultanate, beyond North India, was the most important achievement.
Alauddin first began his territorial conquest with a campaign against Gujarat.
The riches of Gujarat were to pay for his future conquests and her sea port was to ensure a regular supply of Arab horses for his army.
In AD 1299, an army under two of Alauddin’s noted generals Ulugh Khan and Nusarat Khan marched against Gujarat. Rai Karan the ruler of Gujarat fled, the temple of Somnath was captured.
Even the wealthy Muslim merchants were not spared.
Many slaves were captured.
Malik Kafur was one among them who later became the trusted commander of the Khalji forces and led the invasions to South India.
After the annexation of Gujarat, Alauddin turned his attention towards Rajasthan.
The capture of Ranthambore was necessary to break the power and morale of the Rajputs.
The immediate cause of attack was that the ruler of Ranthambore Hamirdeva gave shelter to two rebellious Mongol soldiers and refused to hand over them to the Khalji ruler.
Hence an offensive was launched against Ranthambore.
In AD 1303, Alauddin besieged Chittor, another powerful state of Rajputana.
Chittor was renamed Khizrabad after the name of Sultan’s son Khizr Khan.
In AD 1305, Khalji army under Ain-ul-Mulk captured Malwa.
Other states such as Ujjain, Mandu, Dhar and Chanderi were also captured.
After the conquest of Malwa, Alauddin sent Malik Kafur to the South and himself attacked Siwana.
The ruler of Siwana Raja Shital Deva defended the fort bravely but was ultimately defeated.
In AD 1311, another Rajput kingdom Jalor was also captured.
Thus by AD 1311, Alauddin had completed the conquest of large parts of Rajputana and became the master of North India.
Deccan and South India
The wealth of the southern kingdoms attracted Alauddin .
The expeditions to the south were sent under Malik Kafur, a trusted commander of Alauddin who held the office of the Naib.
In AD 1306–07, Alauddin planned fresh campaign in Deccan.
His first target was Rai Karan (the earlier rule of Gujarat), who had now occupied Baglana, and defeated him.
The second expedition was against Rai Ramachandra, the ruler of Deogir who had earlier promised to pay tribute to Sultan but did not pay.
Ramachandra surrendered after little resistance to Malik Kafur and was treated honourably.
Ramachandra was kept a guest at Alauddin’s court and was given a gift of one lakh tankas and the title of Rai Rayan.
He was also given a district of Gujarat and one of his daughters was married to Alauddin.
Alauddin showed generosity towards Ramachandra because he wanted to have Ramachandra as an ally for campaigns in the South.
After AD 1309 Malik Kafur was dispatched to launch campaign in South India.
The first expedition was against Pratab Rudradeva of Warangal in the Telengana area.
The second campaign was against Dwar Samudra and Ma’bar (modern Karnataka and Tamil Nadu).
The ruler of Dwar Samudra, Vir Ballala III agreed to pay tribute to Sultan without any resistance.
In the case of Ma’bar (Pandya Kingdom) a direct decisive battle could not take place.
However, Kafur plundered as much as he could including a number of wealthy temples such as that of Chidambaram.
Alauddin’s forces under Malik Kafur continued to maintain a control over the Deccan kingdoms.
Following the death of Alauddin in AD 1316, the Delhi Sultanate was plunged into confusion.
Only four years after the death of Alauddin, the Khalji dynasty came to end and power passed into the hands of the Tughlaqs.