Throughout its history, Transylvania has been dominated by several different peoples and countries. Once the nucleus of the Kingdom of Dacia, in 106 AD Transylvania was conquered by the Roman Empire. After the Roman legions withdrew in 271 AD, it was successively run by various tribes such as Visigoths, Huns, Gepids, Avars, Slavs and Bulgarians.
Towards the end of the 9th century when the Hungarians stopped in this part of Europe, Transylvania was ruled by Wallachian Voivode Gelu. Kingdom of Hungary firmly established its control over Transylvania in 1003, when , according to legend, King Stephen I defeated the prince entitled or named Gyula. Between 1003 and 1526, Transylvania was a voivodeship in the Kingdom of Hungary, led by a voivode appointed by the King of Hungary. In 1571 Transylvania was transformed into a Principality primarily ruled by Hungarian princes. For most of this period, Transylvania, maintained its internal autonomy but was under the suzerainty of the Ottoman Empire.
The Habsburgs acquired the territory shortly after the Battle of Vienna in 1683. In 1687, the rulers of Transylvania recognized the suzerainty of the Habsburg emperor Leopold I, and the region was officially attached to the Habsburg Empire. In 1699 the Turks legally conceded their loss of Transylvania in the Treaty of Karlowitz; however, some anti-Habsburg elements within the principality only submitted to the emperor in the 1711 Peace of Satu Mare. In 1867 the Principality of Transylvania was absorbed into the Hungarian part of the newly established Austro-Hungarian Empire.
Following defeat in World War I, Austria-Hungary disintegrated. The Romanian majority in Transylvania elected representatives who on the 1st of December 1918 proclaimed Union with Romania. The Proclamation was adopted by the Deputies of the Romanians from Transylvania, and supported one month later by the vote of the Deputies of the Saxons from Transylvania. In 1920, the Treaty of Trianon established new border between Romania and Hungary, leaving whole Transylvania within Romanian state. In August 1940, with the support of Germany and Italy, Hungary gained about 40% of Transylvania. That territory was assigned back to Romania in 1945 and this was confirmed in the 1947 Paris Peace Treaties.