"As early as the thirteenth century, thinkers like Nur-ud Din Mubarak Ghaznavi, working at the court of Sultan Iltutmish [ruled 1211-1236] set the aggressive tone of Islamic presence in India. Nur-ud Din elaborated the doctrine of Din Panahi [protection of religion], by which Islam had to be defended from the defiling Hindus who were idolaters who must be kept in their place, and insulted, disgraced, dishonoured and defamed. Ziauddin Barani [Diyā al-Dīn Baranī: 1285-1357] who was an Indian jurist, historian, political thinker, writer, and a companion of Sultan Muhammad b. Tughluq [1309 –1388], wrote a Fürstenspiegel, a Mirror of Princes, akin to Machiavelli’s The Prince, the Fatāwā-yi Djahāndārī, in order to educate the de facto rulers of the day, the sultans, in their duty towards Islam in an age of corruption. Barani advises sultans to enforce the sharī‘a, to curb unorthodoxy ( especially speculative philosophy, falsafa), to degrade the infidel, who must be treated harshly. The Sultans must fight like the Prophet until all people affirm that “there is no God but Allah.” It is the duty of Muslim rulers to overthrow infidelity, uproot it completely, and apply the Holy Law, the Sharia on all. Firuz Shah Tughlaq (1309 – 1388), the Turkic Muslim who reigned over the Sultanate of Delhi (1351-1388) carried on the intolerant tradition of the early invaders, and believed that by extirpating Hinduism wherever possible he served God."