Transylvania as originally defined in Treaty of Trianon, 27 years earlier, thus confirming the return of Northern Transylvania to Romania. From 1947 to 1989, Transylvania, along with the rest of Romania, was under a communist regime. The ethnic clashes of Târgu Mureș occurred between ethnic Romanians and Hungarians in March 1990 after the fall of the communist regime and became most notable inter-ethnic incident in the post-communist era. The Transylvanian Plateau, high, is drained by the Mureș, Someș, Criș, and Olt rivers, as well as other tributaries of the Danube. This core of historical Transylvania roughly corresponds with nine counties of
Transylvania their loss of Transylvania in the Treaty of Karlowitz; however, some anti-Habsburg elements within the principality submitted to the emperor only in the 1711 Peace of Szatmár, and Habsburg control over Principality of Transylvania was consolidated. The Grand Principality of Transylvania was reintroduced 54 years later in 1765. The Hungarian revolution against the Habsburgs started in 1848. The revolution in the Kingdom of Hungary grew into a war for the total independence from the Habsburg dynasty. Julius Jacob von Haynau, the leader of the Austrian army was appointed plenipotentiary to restore order in Hungary after the conflict. He ordered the