Tabaqat-i Nasiri, written by the Sultan's court historian Minhaj-i-Siraj, calls him a son (ibn) of Iltutmish.

[2] According to Minhaj's account, Nasiruddin was born in the year of 626 Hijri (1229-1230 CE), in Delhi's Kasr-Bagh (the Garden Castle).

[5][non-primary source needed] He was born sometime after the untimely death of Iltutmish's eldest son and heir apparent Nasir-ud-din Mahmud Shah.

For example, historians K. A. Nizami and J. L. Mehta believe that it is unlikely that Iltutmish sent his own son away from Delhi to the Loni village instead of bringing him up at the royal palace.

Plus, Minhaj states that in 1225 CE, Sultan Nasiruddin's mother married an office named Qutlugh Khan.

Both the brothers remained in confinement until September 1243, when Masud ordered them to be released and conferred upon Mahmud the city of Bharaij and its dependencies.