After a brief reign, his brother Pir Ahmet Bey lost most his beylik (principality) to the Ottoman Empire, and both brothers escaped to Akkoyunlu Turkmen's territory.

Although they weren't able to regain their losses, Kasım allied himself with Republic of Venice, and with the help of a Venetian navy, he was briefly able to keep Silifke and the Mediterranean coast of the beylik.

However, following the campaigns of Gedik Ahmed Pasha of the Ottoman Empire, he lost all of his possessions in 1475.

After Cem escaped and took refuge with the Knights of Rhodes, Kasım acknowledged Ottoman suzerainty.

This biography of a member of an Asian royal house is a stub.