Siemowit IV Duke of Masovia (1352–1426) Parents Euphemia of Opava Siemowit III, Duke of Masovia Children Anna of Masovia Jadwiga of Masovia Casimir II of Masovia Władysław I of Masovia Amelia of Masovia Euphemia of Masovia Maria of Masovia Trojden II of Płock Siemowit V of Masovia Catherine of Masovia Aleksander Mazowiecki Cymburgis of Masovia Siblings Euphemia of Masovia Henry of Masovia Margaret of Masovia Janusz I of Warsaw Stanisław Siemowit of Masovia Partners Alexandra of Lithuania
