Duchy of Kuyavia
The Duchy of Kuyavia was a district principality in the Central Europe, in the region of Kuyavia. Its capital was Inowrocław. It was formed in 1230 from the part of the Duchy of Masovia. In 1231, duchies of Sieradz and Łęczyca, had been formed from the part of the state. The duchy existed until 1367 when it was partitioned between duchies of Inowrocław and Brześć Kujawski. Its only ruler was the duke Casimir I of Kuyavia of the Piast dynasty.