In the year A.D. 1202, when Qulb-ud-Din captured Kalinjar, after the temples had been convened into mosques, and the very name of idolatry was annih… - Qutb-ud-din Aibak

Qutbuddin Aibak's conquests (c. 1200-10) included Gwalior, parts of Bundelkhand, Ajmer, Ranthambhor, Anhilwara as well as parts of U.P. and Malwa. In Naharwala alone 50,000 persons were killed during Aibak's campaign. No wonder that besides earning the honorific of lakhbakhsh (giver of Lakhs) he also earned the nickname of killer of lakhs.

Hindu learning in general was suppressed since Hindu and Buddhist schools were attached to temples and monasteries. These were regularly destroyed from the very beginning and with them schools of learning. Qutbuddin Aibak razed the Sanskrit College of Vishaldeva at Ajmer and in its place built a mosque called Arhai din ka Jhonpra. In the east Ikhtiyauddin Bakhtiyar Khalji sacked the Buddhist university centres in Bihar like Odantapuri, Nalanda and Vikramshila between 1197-1202.

He then marched and encamped under the fort of Delhi... The city and its vicinity were freed from idols and idols-worship, and in the sanctuaries of the images of the Gods, mosques were raised by the worshippers of one God.'...
'Kutbu-d din built the Jami' Masjid at Delhi, and adorned it with stones and gold obtained from the temples which had been demolished by elephants, and covered it with inscriptions in Toghra, containing the divine commands.