Transylvania was a country located on Earth which eventually became part of Romania.

Fenric transported Ingiger from the far future to 9th century Transylvania. (TV: The Curse of Fenric)

In the 15th century, Ungro-Wallachia, ruled by Dracula, bordered Transylvania. (AUDIO: Son of the Dragon)

In 1897, Count Frederick von Dracula travelled from Transylvania to London to confront Bram Stoker, the author of Dracula, which he felt dishonoured his family name. Stoker was saved by his wife Florence, who summoned a flock of bats to carry Dracula back to Transylvania. (COMIC: Bat Attack!)

The Doctor once gave the people of Transylvania a fright when, after fiddling with the TARDIS' psychic circuits, nobody could see his reflection. (PROSE: Borrowed Time)