History of Transylvania union of Transylvania with Romania in Alba Iulia on 1. December 1918.; Bessarabia, having declared independence from Russia in 1917 at the Conference of the Country (Sfatul Țării), called in Romanian troops to protect the province from the Bolsheviks. The union of the Transylvania, Maramureș, Crișana and Banat regions with the Old Kingdom of Romania was ratified in 1920 by the Treaty of Trianon, which recognised the sovereignty of Romania over these regions and settled the border between the Republic of Hungary and the Kingdom of Romania. The union of Bukovina and Bessarabia with Romania was ratified in 1920 by
Transylvania For most of this period, Transylvania, maintaining its internal autonomy, 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. The Habsburgs acknowledged Principality of Transylvania as one of the Lands of the Crown of Saint Stephen, but the territory of principality was administratively separated from Habsburg Hungary and subjected to the direct rule of the emperor's governors. In 1699 the Turks legally acknowledged