Delhi Sultanate
During the last quarter of the 12th century, Muhammad of Ghor invaded the Indo-Gangetic plain, conquering in succession Ghazni, Multan, Sindh, Lahore, and Delhi. Qutb-ud-din Aybak, one of his generals proclaimed himself Sultan of Delhi. In the 13th century, Shamsuddīn Iltutmish (1211–1236), a former slave-warrior, established a Turkic kingdom in Delhi, which enabled future sultans to push in every direction; within the next 100 years, the Delhi Sultanate extended its way east to Bengal and south to the Deccan, while the sultanate itself experienced repeated threats from the northwest and internal revolts from displeased, independent-minded nobles. The sultanate was in constant flux as five dynasties rose and fell: the Slave dynasty (1206–90), Khalji dynasty (1290–1320), Tughlaq dynasty (1320–1413), Sayyid dynasty (1414–51), and Lodi dynasty (1451–1526). The Khilji dynasty, under 'Alā'uddīn (1296–1316), in bringing most of South India under its control for a time, although conquered areas broke away quickly. Power in Delhi was often gained by violence—nineteen of the thirty-five sultans were assassinated—and was legitimized by reward for tribal loyalty. Factional rivalries and court intrigues were as numerous as they were treacherous; territories controlled by the sultan expanded and shrank depending on his personality and fortunes.
Both the Qur'an and sharia (Islamic law) provided the basis for enforcing Islamic administration over the independent Hindu rulers, but the sultanate made only fitful progress in the beginning, when many campaigns were undertaken for plunder and temporary reduction of fortresses. The effective rule of a sultan depended largely on his ability to control the strategic places that dominated the military highways and trade routes, extract the annual land tax, and maintain personal authority over military and provincial governors. Sultan 'Ala ud-Din made an attempt to reassess, systematize, and unify land revenues and urban taxes and to institute a highly centralized system of administration over his realm, but his efforts were abortive. Although agriculture in North India improved as a result of new canal construction and irrigation methods, including what came to be known as the Persian wheel, prolonged political instability and parasitic methods of tax collection brutalized the peasantry. Yet trade and a market economy, encouraged by the free-spending habits of the aristocracy, acquired new impetus both inland and overseas. Experts in metalwork, stonework, and textile manufacture responded to the new patronage with enthusiasm. In this period Persian language and many Persian cultural aspects became dominant in the centers of power in India.
Read more about this topic: Islamic Rulers In The Indian Subcontinent