This one is a bit tricky to answer, I assume that what you mean, when you say ' are there any new countries that were not once a part of another country', you mean that were once a country themselves and were forcefully taken from the previous government? If that is roughly correctly, then yes, there is at least one. The Principality of Sealand : During World War II, the United Kingdom decided to establish a number of military bases, the purpose of which was to defend England against German air raids. These sea forts housed enough troops to man and maintain artillery designed to shoot down German aircraft and missiles. They were situated along the east coast of England on the edge of the English territorial waters. After WWII ended, the troops were withdrawn from all bases by the British Admiralty. None of them was ever used by the United Kingdom again, leaving the forts deserted and abandoned. On 2 September 1967, former English major Paddy Roy Bates formally occupied the island and settled there with his family. After intensive discussions with skillful English lawyers, Roy Bates proclaimed the island his own state. Claiming jus gentium, he bestowed upon himself the title of Prince and the title of Princess to his wife and subsequently made the state the Principality of Sealand. Roy Bates, henceforth Roy of Sealand, exerted state authority on the island and thus was an absolute sovereign. The royal family and other persons that have declared loyalty to Sealand have occupied Sealand ever since. You got to admire a self made prince...