According to Selçukname the history book written by Yazıcıoğlu Ali, an Ottoman historian of the early 15th century, when Keykubat travelled to east to take precations against a possible Mongol invasion, his regent in west Anatolia was Husam al-Din Choban with Ertuğrul (father of Osman I of the Ottoman Empire) and his brother being his subordinates.[3]