The Duchy of Bohemia, also later referred to in English as the Czech Duchy,[1][2] (Czech: České knížectví) was a monarchy and a principality of the Holy Roman Empire in Central Europe during the Early and High Middle Ages. It was formed around 870 by Czechs as part of the Great Moravian realm. The Bohemian lands separated from disintegrating Moravia after Duke Spytihněv swore fidelity to the East Frankish king Arnulf in 895.