The Kingdom of Goritania, which later became the People's Republic of Goritania, was a country which made a bargain with the Mefistole which made it invisible. By the 1780s, the country had not had a war in five centuries and its flag was a declaration of eternal peace.
Rudolph was Crown Prince in the 1780s when the Tenth Doctor, who found it with difficulty, and Donna Noble visited. Six months after their departure, Goritania changed from a monarchy to a republic, becoming the People's Republic of Goritania. (AUDIO: Death and the Queen)