According to the article on "Architecture" in Banglapedia, "Unlike European periodisation, the medieval period in Indian history is generally regarded to have started with the coming of the Muslims, particularly the conquest of Delhi towards the end of the twelfth century by the Ghorids of Afghanistan." The "generally regarded" is dubious.
Chakravarti, Mahadev, The Concept of Rudra-Śiva Through the Ages, pp. 153-154, 1986, Motilal Banarsidass Publ., ISBN8120800532, 9788120800533, google books
Examples: Farooqui; Radhey Shyam Chaurasia, History of Medieval India: From 1000 A.D. to 1707 A.D., 2002, google books; Satish Chandra, Medieval India: From Sultanat to the Mughals, 2004 (2 vols), google books; Upinder Singh, A History of Ancient and Early Medieval India: From the Stone Age to the 12th century, 2008, google books
