After the Battle of Mohács (1526), the division of the Kingdom of Hungary into two parts was a long process with grave inner conflicts. The Hungarian Estates chose two kings after the battle : János Szapolyai I (John I Szapolyai, r. 1526-1540) and Habsburg Ferdinand (r. 1527-1564). From the very beginning, the dual coronation made it virtually inevitable that if neither were to be able to defeat the other, the territories under their rule would also split in time. This was laid down in the Treaty of Várad in 1538 (now Oradea/Nagyvárad in Romania), which divided the territories between the two kings. The eastern parts of Hungary finally seceded after Buda was conquered by the Ottoman Empire in 1541. After several more conflicts and some diplomatic intrigues (particularly with the king of France), the two parts found a compromise. The Principality of Transylvania was finally created through the Treaty of Speyer (1570/71), which was signed by János Zsigmond Szapolyai II (John Sigismund II Szapolyai, r. 1559-1571) and Habsburg Maximilian (r. 1564-1576). The treaty codified the relationship between the two regions and their rulers. According to the treaty, János Zsigmond II gave up his title of elected king (electus rex) and took instead the title of Prince of Transylvania and the annexed parts of Hungary (Princeps Transylvaniae et Partium regni Hungariae eidem annexarum). The treaty declared that if the prince were to die without an heir, Transylvania, as a real and inseparable part of the Holy Crown of Hungary (tanquam verum et inseparabile membrum) would be ruled by the King of Hungary.