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
History of Transylvania the successful Aster Revolution in Budapest brought the left liberal, pro-Entente count Mihály Károlyi to power as prime minister of Hungary. Influenced by Woodrow Wilson's pacifism, Károlyi ordered the disarmament of Hungarian Army. The Károlyi government outlawed all Hungarian armed associations and proposals intending to defend the country. The resulting Treaty of Bucharest was denounced in October 1918 by the Romanian government, which then re-entered the war on the Allied side and advanced to the Mureș (Maros) river in Transylvania. The leaders of Transylvania's National Party met and drafted a resolution invoking the right of self-determination (influenced by Woodrow Wilson's