Siemowit I of Masovia Polish duke (1215–1262) Parents Konrad I of Masovia Agafia of Rus Children Konrad II of Masovia Bolesław II of Masovia Siblings Judith of Masovia Bolesław I of Masovia Casimir I of Kuyavia Eudoxia of Masovia Dubrawka of Masovia Partners Pereiaslawa of Galicia
