an Entity references as follows:
The Duchy of Pomerania (German: Herzogtum Pommern; Polish: Księstwo Pomorskie; Latin: Ducatus Pomeraniae) was a duchy in Pomerania on the southern coast of the Baltic Sea, ruled by dukes of the House of Pomerania (Griffins). The country had existed in the Middle Ages, in years 1121–1160, 1264–1295, 1478–1531 and 1625–1637.