Mention the main reason for the …

The Delhi Sultanate was an Islamic empire based in Delhi that stretched over large parts of the Indian subcontinent for 320 years (1206–1526).[5][6] Five dynasties ruled over the Delhi Sultanate sequentially: the Mamluk/ Slave dynasty (1206–1290), the Khilji dynasty (1290–1320), the Tughlaq dynasty (1320–1414),[7] the Sayyid dynasty (1414–1451), and the Lodi dynasty (1451–1526). Delhi Sultanate 1206–1526 Delhi Sultanate reached its zenith under the Turko-Indian Tughlaq dynasty.[1] Capital Lahore (1206–1210) Badayun (1210–1214) Delhi (1214–1327) Daulatabad (1327–1334) Delhi (1334–1506) Agra (1506–1526) Common languagesPersian (official),[2] Hindustani (since 1451)[3]Religion Sunni IslamGovernmentSultanateSultan  • 1206–1210 Qutb al-Din Aibak (first) • 1517–1526 Ibrahim Lodi (last)LegislatureCorps of FortyHistorical eraMiddle Ages • Independence[4] 12 June 1206 • Battle of Amroha 20 December 1305 • Battle of Panipat 21 April 1526CurrencyTaka Preceded bySucceeded byGhurid dynastyGahadavalaChandela dynastyParamara dynastyDeva dynastySeuna (Yadava) dynastyKakatiya dynastyMusunuri NayaksVaghela dynastyYajvapala dynastyChahamanas of RanastambhapuraMughal EmpireBengal SultanateBahamani SultanateGujarat SultanateMalwa SultanateVijayanagara EmpireToday part ofBangladesh India Nepal Pakistan It covered parts of India, Pakistan, Bangladesh and some parts of southern Nepal. As a successor to the short-lived Ghurid empire, the Delhi Sultanate was originally one among a number of principalities ruled by Turkic slave-generals of Muhammad Ghori, who had conquered large parts of northern India, including Yildiz, Aibek and Qubacha, that had inherited and divided the Ghurid territories amongst themselves.[8] After a long period of infighting, the Mamluks were overthrown in the Khalji revolution which marked the transfer of power from the Turks to a heterogenous Indo-Mussalman nobility.[9][10] Both of the resulting Khalji and Tughlaq dynasties respectively saw a new wave of rapid Muslim conquests deep into South India.[11] The sultanate finally reached the peak of its geographical reach during the Tughlaq Dynasty, occupying most of the Indian subcontinent.[12] This was followed by decline due to Hindu reconquests, states such as the Vijayanagara Empire and Mewar asserting independence, and new Muslim sultanates such as the Bengal Sultanate breaking off.[13][14] In 1526, the Sultanate was conquered and succeeded by the Mughal Empire. The sultanate is noted for its integration of the Indian subcontinent into a global cosmopolitan culture[15] (as seen concretely in the development of the Hindustani language[16] and Indo-Islamic architecture[17][18]), being one of the few powers to repel attacks by the Mongols (from the Chagatai Khanate)[19] and for enthroning one of the few female rulers in Islamic history, Razia Sultana, who reigned from 1236 to 1240.[20] Bakhtiyar Khalji's annexations were responsible for the large-scale desecration of Hindu and Buddhist temples[21] (leading to the decline of Buddhism in East India and Bengal[22][23]), and the destruction of universities and libraries.[24][25] Mongolian raids on West and Central Asia set the scene for centuries of migration of fleeing soldiers, learned men, mystics, traders, artists, and artisans from those regions into the subcontinent, thereby establishing Islamic culture in India.[26][27]