The sultan returned to Ghazni and , leaving Qutb-ud-din in charge , moved east to Bengal , destroying centers of Buddhism such as the University of Nalanda .
While leaving Qutb-ud-din in charge the sultan returned to Gahzni and moved east to Bengal destroying centers of Buddhism such as the University of Nalanda because he did not want more students or Indians learning about what he viewed as a weak and soft religion .