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.
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.