Euphemia of Masovia Polish noblewoman (1395-1447) (1395–1447) Parents Alexandra of Lithuania Siemowit IV Children Przemysław II, Duke of Cieszyn Wenceslaus I, Duke of Cieszyn Alexandra of Teschen Władysław of Głogów Bolesław II, Duke of Cieszyn Siblings Trojden II of Płock Jadwiga of Masovia Amelia of Masovia Cymburgis of Masovia Casimir II of Masovia Catherine of Masovia Władysław I of Masovia Maria of Masovia Siemowit V of Masovia Anna of Masovia Aleksander Mazowiecki Partners Bolesław I, Duke of Cieszyn