After the Battle of Bornhöved (1227), Margrave John I staked his claim to Pomerania, receiving it as a fief from Emperor Frederick II in 1231. The middle of the 13th century was a time of important developments for the Ascanian House, as it won Stettin (Szczecin) and the Uckermark (1250), although the former was later lost to the Duchy of Pomerania . 
The short-lived Margraviate of Brandenburg-Küstrin was set up as a secundogeniture of the House of Hohenzollern. 1535–1571: John the Wise, Margrave of Brandenburg-Küstrin (son of Joachim I Nestor, Elector of Brandenburg). He died without issue. The Margraviate of Brandenburg-Küstrin was absorbed in 1571 into Brandenburg.
Born in Cölln on the Spree (today part of Berlin), George William was the son of John Sigismund, Margrave of Brandenburg and Anna of Prussia. His maternal grandfather was Albert Frederick, Duke of Prussia. In 1616, he married Elisabeth Charlotte of the Palatinate. Their only son Frederick William would later be known as the "Great Elector".
From 1695 Margrave Christian Ludwig served as a general lieutenant at the Stettin garrison and commander of the Old Prussian Infantry Regiment No.7. He also acted as administrator of the secularised Prussian Principality of Halberstadt and was awarded the Order of the Black Eagle for his merits.
As Brandenburg-Küstrin the Neumark formed an independent state of the Holy Roman Empire of the German Nation from 1535 to 1571; after the death of the margrave John, a younger son of Joachim I Nestor, Elector of Brandenburg, it returned to Elector John George, the margrave's nephew and Joachim I Nestor's grandson.
Frederick III (Danish: Frederik; 18 March 1609 – 9 February 1670) was king of Denmark and Norway from 1648 until his death in 1670. He also governed under the name Frederick II as diocesan administrator (colloquially referred to as prince-bishop) of the Prince-Bishopric of Verden (1623–29 and again 1634–44), and the Prince-Archbishopric of Bremen (1635–45).
Her parents were Joachim Frederick, Margrave of Brandenburg and his first wife Catherine of Brandenburg-Küstrin. Christian met her on his journey in Germany in 1595 and decided to marry her. In 1596, Anne Catherine and her parents were present at his coronation, and the next year, the marriage was arranged.