"The first thing the Muslim Sultanate of Delhi started on was construction of impressive buildings. The first sultan Qutbuddin Aibak had to establish Muslim power in India and to raise buildings "as quickly as possible, so that no time might be lost in making an impression on their newly-conquered subjects". Architecture was considered as the visual symbol of Muslim political power. It denoted victory with authority. The first two buildings of the early period in Delhi are the Qutb Minar and the congregational mosque named purposefully as the Quwwat-ul-Islam Masjid. This mosque was commenced by Aibak in 592/1195. It was built with materials and gold obtained by destroying 27 Hindu and Jain temples in Delhi and its neighborhood. A Persian inscription in the mosque testifies to this. The Qutb Minar, planned and commenced by Aibak sometime in or before 1199 and completed by Iltutmish, was also constructed with similar materials, "the sculptured figures on the stones being either defaced or concealed by turning them upside down". A century and a quarter later Ibn Battutah describes the congregational mosque and the Qutb Minar. "About the latter he says that its staircase is so wide that elephants can go up there." About the former his observations are interesting. "Near the eastern gate of the mosque their lie two very big idols of copper connected together by stones. Every one who comes in and goes out of the mosque treads over them. On the site of this mosque was a bud khana, that is an idol house. After the conquest of Delhi it was turned into a mosque."

“Qutbuddin Aibak's conquests 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 he also earned the nickname of killer of lakhs.”

“The congregational mosque at Delhi named, purposefully, as the Masjid Quwwatul Islam , was commenced by Aibak in 592/1195 within two years of its conquest. It was built with materials and gold obtained by destroying 27 Hindu and Jain temples in Delhi and its neighbourhood. A Persian inscription in the mosque testifies to this. The mosque at Ajmer erected by Qutbuddin Aibak soon after its occupation and known as the Arhai din ka Jhonpra, was also built from materials obtained from demolished temples. The Qutb Minar, planned and commenced by Aibak sometime in or before 1199 and completed by Iltutmish, was also constructed with similar materials, “the sculptured figures on the stones being either defaced or concealed by turning them upside down.” “In this improvisation,” rightly observes Habibullah, “was symbolised the whole Mamluk history”.”

““When Qutbu’d-Din, the commander-in-chief of Muizzu’d-Din Sam alias Shihabu’d-Din Ghuri, conquered Delhi in AH 587 corresponding to AD 1191 corresponding to 1248 Bikarmi, this idol-house was converted into a mosque. The idol was taken out of the temple. Some of the images sculptured on walls or doors or pillars were effaced completely, some were defaced. But the structure of the idol-house kept standing as before. Materials from twenty-seven temples, which were worth five crores and forty lakhs of Dilwals, were used in the mosque, and an inscription giving the date of conquest and his own name was installed on the eastern gate…“When Malwah and Ujjain were conquered by Sultan Shamsu’d-Din in AH 631 corresponding to AD 1233, then the idol-house of Mahakal was demolished and its idols as well as the statue of Raja Bikramajit were brought to Delhi, they were strewn in front of the door of the mosque…”“In books of history, this mosque has been described as Masjid-i-Adinah and Jama‘ Masjid Delhi, but Masjid Quwwat al-Islam is mentioned nowhere. It is not known as to when this name was adopted. Obviously, it seems that when this idol-house was captured, and the mosque constructed, it was named Quwwat al-Islam…”

“In 1195 when Raja Bhim was attacked by Aibak 20,000 slaves were captured, and 50,000 at Kalinjar in 1202. “The temples were converted into mosques,” writes Hasan Nizami, “and the voices of the summoners to prayer ascended to the highest heavens, and the very name of idolatry was annihilated.”... Farishtah specifically mentions that during the capture of Kalinjar “fifty thousand kaniz va ghulam, having suffered slavery, were rewarded with the honour of Islam.” Thus enslavement resulted in conversion and conversion in accelerated growth of Muslim population.”

“Women and children were the prize of the warriors, and as early as the days of Qutbuddin Aibak "even a poor Muslim householder became owner of numerous slaves.”

“For instance, when Muhammad Ghauri and Qutbuddin Aibak mounted a combined attack on the Khokhars of the Salt Range , “great plunder was taken and many captives, so that five Hindu captives could be bought for a dinar”. Captives were so plentiful that they were also sent “to sell in Khurasan, not long after.”