 In March–April 1229, Iltutmish's son Nasiruddin Mahmud, who had been governing Bengal since 1227, died unexpectedly.Taking advantage of this, Malik Ikhtiyaruddin Balkha (or Bilge Malik), who seems to have been a former officer of Iltutmish, usurped the authority in Bengal.Iltutmish invaded Bengal, and defeated him in 1230.