Ala-ud-din Khilji succeeded in conquering most parts of India. Larger portion of north India was annexed to his empire. He also defeated many rulers in south India except the Pandyas, who were forced to accept his suzerainty. The places in north India which were incorporated within his empire were Gujarat, Jaisalmer, Ranthambhor, Chittor, Malwa, Siwana, and Jalore. The kingdoms in south India that were under his dominion were the Hoysala kingdom and the kingdom of Devagari.

Gujarat was a prosperous state and in the latter half of 1298 A.D. Ala-ud-din Khilji sent an expedition under Ulugh Khan and Nusrat Khan to Gujarat. On the way, Jaisalmer was also conquered. At that time Karna was the ruler of Gujarat who was defeated by the army of Ala-ud-din. Ranthambhor was a stronghold of Chauhana Rajputs. Ala-ud-din wanted to conquer it because of its strategical importance. He dispatched Ulugh Khan and Nusrat Khan to attack Ranthambhor. Though the fort was besieged but Nusrat Khan was killed in the combat and the invaders were forced to retreat. Then Ala-ud-din himself besieged the fort. It took one long year for Ala-ud-din to successfully capture the fort.

Chittor was another centre for the powers of the Rajputs. The fort of Chittor was constructed on a high hill and was regarded as unconquerable. Ala-ud-din attacked Chittor in 1303 A.D. and besieged the fort. A part of Malwa was already in the hands of the Sultan but it was never completely conquered. Ala-ud-din sent Ain -ul -mulk, governor of Multan, to attack Malwa, who besieged the fort of Mandu. Siwana was attacked in 1308 A.D. by Ala-ud-din and was eventually captured. The conquest of Jalor completed the conquest of Rajasthan by Ala-ud-din Khilji. Bundi, Mandor, Tonk and probably Jodhpur also surrendered to Ala-ud-din. All the strong forts of Rajasthan were captured by him and that provided safety to the passages towards Gujarat and South India.

In the beginning of the 14th century Ala-ud-din decided to conquer the south India. The purpose of Ala-ud-din in attacking the kingdoms of south India was two fold. The south was not plundered so far by Muslim invaders and therefore possessed vast wealth and therefore he wanted to plunder the resources of south India. His other aim was to force them to accept his suzerainty and get annual tribute from them which would be a regular source of wealth for him and would also increase his prestige in India.

Ala-ud-din sent Malik Kafur to attack Telangana in 1309 A.D. he conquered Sirbar on the way and reached the capital city of Warangal in 1310 A.D. the capital was well defended by two round walls, the outer one being that of earth and the inner one that of stone and also by two moats filled with water between the two walls. The ruler of Telengana accepted the suzerainty of Ala-ud-din and agreed to pay annual tribute and gave one hundred elephants, seven hundred horses and all his accumulated treasure as gift. Vir Ballala of the Hoysala Empire also agreed for peace with Ala-ud-din and agreed to pay annual tribute.

Ala-ud-din's policy towards the south was successful. He succeeded in fulfilling his object. Ala-ud-din was the first Muslim Sultan of Delhi who dared to attack south India and was successful. Most of the kingdoms of the south were forced to accept his suzerainty and pat annual tribute to him.

Thus Ala-ud-din Khilji succeeded in establishing a vast empire in India. Towards the North West it extended up to the Indus River and after 1306 A.D. even Kabul and Ghazni came under his sphere of influence. Towards the east it extended up to Avadh and Orissa. Punjab in the north to the Vindhyas in the south, all territories formed part of his empire. In the south except the Pandya ruler, all of them accepted his supremacy. The empire of Ala-ud-din Khilji was certainly more extensive as compared to all other previous Muslim rulers of Delhi.