Qutbuddin Aibak was the first sovereign Sultan of Delhi, having been a slave general of Muhammad Ghori who established independence after his master's death in 1206. He founded the Mamluk Dynasty (Slave Dynasty) and began construction of the Qutub Minar. Alauddin Khalji came later (13th century), Balban was a powerful Sultan but not the first, and Iltutmish was Aibak's son-in-law and successor.