Historian K. A. Nizami theorizes that Sultan Mu'izz ad-Din never appointed Aibak as his successor in India: the slave-general acquired this position "after" the Sultan's death through use of diplomacy and military power. The Sultan's unexpected death left three of his main slave-generals - Aibak, Taj al-Din Yildiz, and Nasir ad-Din Qabacha - in positions of power. During his last years, the Sultan was disappointed in his family and his chiefs, and trusted only his slaves, whom he thought of as his sons and successors.