Sigismund, Holy Roman Emperor was from 1387 to 1437 also a King of Hungary. Although Hungary's economy continued to flourish, Sigismund's expenses outstripped his income. Social turmoil erupted late in Sigismund's reign as a result of the heavier taxes. Hungary's first peasant revolt was quickly checked, but it prompted Transylvania's Hungarian and German nobles to form the Union of Three Nations, which was an effort to defend their privileges against any power except that of the king.