A cikin karni na 9 mai yiwuwa Mazovia ta kasance a cikin kabilar Mazovians, kuma an shigar da ita cikin kasar Poland a cikin rabin na biyu na karni na 10 karkashin mulkin Piast Mieszko I. Sakamakon rarrabuwar kawuna na Poland bayan mutuwar sarkin Poland. Bolesław III Wrymouth, a cikin 1138 an kafa Duchy na Mazovia, kuma a cikin ƙarni na 12th da 13th ya haɗu da wasu ƙasashe na ɗan lokaci na ɗan lokaci kuma ya jure mamaye Prussians, Yotvingians, da Ruthenia.Don kare sashensa na arewa Conrad I na Mazovia da aka kira a cikin Teutonic Knights a 1226 kuma ya ba su Chełmno Land.Yankin tarihi na Mazovia (Mazowsze) a farkon ya ƙunshi yankuna ne kawai a bankin dama na Vistula kusa da Płock kuma yana da alaƙa mai ƙarfi da Greater Poland (ta hanyar Włocławek da Kruszwica).A zamanin mulkin sarakunan Poland na farko na daular Piast, Płock na ɗaya daga cikin kujerunsu, kuma a kan tudun Cathedral (Wzgórze Tumskie) sun tayar da palatium.A cikin lokacin 1037-1047 shi ne babban birnin mai zaman kansa, jihar Mazovian ta Masław.Tsakanin 1079 da 1138 wannan birni ya kasance babban birnin Poland.