sentences:  The title of king of Hungary was disputed between Zápolya and Ferdinand until 1540.After the seizure of Buda by the Ottomans in 1541, the West and North recognized a Habsburg as king ("Royal Hungary"), while the central and southern counties were annexed by the Ottoman Sultan and the east was ruled by the son of Zápolya under the name Eastern Hungarian Kingdom which after 1570 became the Principality of Transylvania.Whereas a great many of the 17,000 and 19,000 Ottoman soldiers in service in the Ottoman fortresses in the territory of present-day Hungary were Orthodox and Muslim Balkan Slavs, Southern Slavs were also acting as akıncıs and other light troops intended for pillaging in the territory of present-day Hungary.