Lokacin da Ottomans suka kashe babban sojojin Hungary da Sarki Louis II Jagiello a yakin Mohács na 1526, John Zápolya - voivod na Transylvania, wanda ya yi adawa da maye gurbin Ferdinand na Ostiriya (daga baya Emperor Ferdinand I) zuwa kursiyin Hungarian - ya sami fa'ida. na karfin sojansa.Sa’ad da aka zaɓi John I ya zama sarkin Hungary, wata ƙungiya ta amince da Ferdinand.A cikin gwagwarmayar da ta biyo baya Zápolya ya sami goyon bayan Sultan Suleiman I, wanda (bayan mutuwar Zápolya a 1540) ya mamaye tsakiyar Hungary don kare ɗan Zápolya John II.John Zápolya ya kafa Masarautar Hungarian ta Gabas (1538-1570), wanda daga ita ce Sarautar Transylvania ta tashi.An kirkiro sarautar ne bayan sanya hannu kan yarjejeniyar Speyer a shekara ta 1570 da sarki John II da sarki Maximiliam na biyu suka yi, don haka John Sigismund Zápolya, sarkin Hungarian na Gabas ya zama yarima na farko na Transylvania.A cewar yarjejeniyar, masarautar Transylvania da sunan zama wani yanki na Masarautar Hungary a ma'anar dokar jama'a.Yarjejeniyar Speyer ta jaddada ta hanya mai mahimmanci cewa dukiyar John Sigismund na Mai Tsarki Crown na Hungary ne kuma ba a ba shi izinin raba su ba.^[68]