Qutb al-Din Aibak initiated the construction of the Qutub Minar. It is known that Aibak started the construction of Qutb Minar but died without completing it. It was later completed by his son-in-law, Iltutmish. The Quwwat-ul-Islam (Might of Islam) Mosque was built by Aibak, now a UNESCO world heritage site. The Qutub Minar Complex or Qutb Complex was expanded by Iltutmish, and later by Ala ud-Din Khalji (the second ruler of the Khalji dynasty) in the early 14th century. During the Mamluk dynasty, many nobles from Afghanistan and Persia migrated and settled in India, as West Asia came under Mongol siege.