Transylvania modern Romania. The plateau is almost entirely surrounded by the Eastern, Southern and Romanian Western branches of the Carpathian Mountains. The area includes the Transylvanian Plain. Other areas to the west and north are widely considered part of Transylvania. In common reference, the Western border of Transylvania has come to be identified with the present Romanian-Hungarian border, settled in the 1920 Treaty of Trianon, though geographically the two are not identical. Ethnographic areas: The area of the historical Voivodeship is . The regions granted to Romania in 1920 covered 23 counties including nearly (102,787–103,093 km in Hungarian sources and 102,200
Transylvania withdrew in 271 AD, it was overrun by a succession of various tribes, bringing it under the control of the Carpi, Visigoths, Huns, Gepids, Avars and Slavs. From 9th to 11th century Bulgarians ruled Transylvania. It is a subject of dispute whether elements of the mixed Daco–Roman population survived in Transylvania through the Post-classical Era (becoming the ancestors of modern Romanians) or the first Vlachs/Romanians appeared in the area in the 13th century after a northward migration from the Balkan Peninsula. There is an ongoing scholarly debate over the ethnicity of Transylvania's population before the Hungarian conquest (see Origin of