The Eastern Hungarian Kingdom (in Hungarian: Keleti Magyar Királyság) is the modern name used to designate the realm of John Zápolya and his son John Sigismund Zápolya, who contested the claims of the House of Habsburg to rule the Kingdom of Hungary from 1526 to 1570. The Zápolyas ruled over an eastern part of Hungary, while the Habsburg kings (Ferdinand and Maximilian) ruled the west. The Habsburgs tried several times to unite all Hungary under their rule, but the Turks prevented this by supporting the Eastern Hungarian Kingdom.