Following the death of Iltutmish, assassination of Saifuddin Aibak and the subsequent ascension of the rebel usurper Awar Khan Aibak, Tughan invaded Bengal and successfully defeated Awar Khan in 1236. Immediately after assuming power, Tughan Khan led a number of expeditions. He established his dominance throughout Bengal, Bihar and Oudh while staying loyal to the Delhi Sultanate.