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 (and briefly under Habsburg suzerainty) until 1602. The younger Stephen Báthory, a Hungarian Catholic who later became King Stephen Báthory of Poland, tried to maintain the religious liberty granted by the Edict of Turda but interpreted this obligation in an increasingly restricted sense. Under Sigismund Báthory, Transylvania entered the Long War, which began as a Christian alliance against the Turks and became a four-sided conflict in Transylvania involving the Transylvanians, Habsburgs, Ottomans and the Romanian voivod of Wallachia led by Michael the Brave. Michael gained control of Transylvania (supported by the Szeklers) in October 1599 after the Battle of Șelimbăr,