Photograph from an album of 80 albumen prints taken by Eugene Clutterbuck Impey. Close-up of the carved decoration of the Alai Darwaza gateway near the Qutub Minar in Delhi. The foundations of Muslim rule in India were laid when Mohammad Ghori conquered north India at the end of the 12th century. When he was assassinated in 1206 his achievements in India were inherited by the commander of his armies, the Turkish slave Qutub-ud-din Aibak who established what came to be known as the Mamluk or Slave Dynasty (1206-90) because his successors were also manumitted slaves. The Qutub Minar complex contains some of the earliest great Islamic monuments of India and construction was initiated here soon after the conquest of Delhi in 1192. More than a hundred years later the complex was enlarged by Alauddin Khalji (reigned 1296-1316). He completed the south gateway to Qutub-ud-din's Quwwat-ul-Islam mosque in 1311. Known as the Alai Darwaza, it is a sandstone cube topped by a shallow dome and is 18.29 ms high. Each facade has a pointed horseshoe arch and squinches (arches set diagonally across the corners of a square chamber) in the interior support the dome.