Virtually every Islamic power thereafter followed the Ghaznavids' practice of using Persian as a courtly language. Delhi became a major centre of Persian literary culture in Hindustan from the 13th century onwards, with the establishment of the Delhi Sultanate by the post-Ghurid Mamluks. The successive Khiljis and Tughluqs sponsored many pieces of literature in the language; celebrated poet Amir Khusrow produced much of his Persian work under their patronage. Between the 13th and 15th centuries, the Turkic rulers of the Delhi Sultanate encouraged the flow of eminent Persian-speaking personalities (such as poets, scribes, and holy people) into the subcontinent, granting them land to settle in rural areas. This flow was increased by the Mongol conquests of the Perso-Islamic world, as many Persian elite sought refuge in North India. Hence the Persian language established itself in court and literature, but also through a sizeable population often associated with Islamic nobility. The Delhi Sultanate was largely the impetus for the spread of Persian, since its borders stretched deep into the subcontinent. In the wake of its gradual disintegration, the various outgrowths of the empire in regions as far as the Deccan and Bengal resultantly adopted Persian.