claim: Paul von Hindenburg was a person.
evidence: The Eastern Hungarian Kingdom -LRB- in Hungarian  : Keleti Magyar Kiralysag -RRB- is the modern name used to designate the realm of John Zapolya and his son John Sigismund Zapolya , who contested the claims of the House of Habsburg to rule the Kingdom of Hungary from 1526 to 1570 .. John Zapolya. John Zapolya. John Sigismund Zapolya. John Sigismund Zapolya. House of Habsburg. House of Habsburg. Kingdom of Hungary. Kingdom of Hungary. The Zapolyas ruled over an eastern part of Hungary , while the Habsburg kings -LRB- Ferdinand and Maximilian -RRB- ruled the west .. Ferdinand. Ferdinand I, Holy Roman Emperor. Maximilian. Maximilian II, Holy Roman Emperor. The Habsburgs tried several times to unite all Hungary under their rule , but the Ottoman Empire prevented this by supporting the Eastern Hungarian Kingdom .. Ottoman Empire. Ottoman Empire. The exact extent of the Zapolya realm was never settled , because the Habsburgs and the Zapolyas both claimed the whole kingdom .. A temporary territorial division was made in the Treaty of Nagyvarad in 1538 .. Treaty of Nagyvarad. Treaty of Nagyvarad. The Eastern Hungarian Kingdom is the predecessor of the Principality of Transylvania -LRB- 1570 -- 1711 -RRB- , established by the Treaty of Speyer -LRB- 1570 -RRB- .. Treaty of Speyer. Treaty of Speyer ( 1570 )