Siemowit V of Masovia Prince of Masovia (1389–1442) Parents Alexandra of Lithuania Siemowit IV Children Margareta of Rawa 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 Euphemia of Masovia Anna of Masovia Aleksander Mazowiecki Partners Margareta of Opava-Ratibor