Janusz I of Warsaw, also known as Janusz I the Old, was a Polish prince member of the House of Piast in the Masovian branch, from 1373/74 Duke of Warsaw and after the division of the paternal inheritance between him and his brother in 1381, ruler over Nur, Łomża, Liw, Ciechanów, Wyszogród and Zakroczym. In addition, he was a vassal of the Polish Kingdom since 1391 for the fief of Podlachia.
Duchy of Masovia was a district principality and a fiefdom of the Kingdom of Poland, existing during the Middle Ages. The state was centered in Mazovia in the northeastern Kingdom of Poland, and during its existence, its capital was located in the Płock, Czersk and Warsaw. It was formed in 1138 from the territories of the Kingdom of Poland, following its fragmentation, that was started by the testament of Bolesław III Wrymouth. The country existed in the years: 1138–1275, 1294–1310, 1370–1381, and 1495–1526, between that time, going through fragmentations of its territory into smaller duchies and its unification. The states formed during its fragmentation were duchies of Kuyavia, Dobrzyń, Czersk, Płock, Warsaw, Rawa and Belz. In 1526, the country was incorporated into the Kingdom of Poland.
Siemowit III of Masovia was a prince of Masovia and a co-regent of the lands of Warsaw, Czersk, Rawa, Gostynin and other parts of Masovia.
Konrad III Rudy, also known in English as Konrad the Red, was a Polish prince and member of the Piast dynasty in the Masovian branch. He was a duke of Czersk, Liw, Warsaw, Nur, Łomża, Ciechanów, Różan, Zakroczym and Wyszogród during 1454-1471 jointly with his brothers, Duke of Płock, Wizna, Płońsk and Zawkrze during 1462-1471, and after the division of the paternal domains in 1471, sole ruler over Czersk and Liw, over Wyszogród during 1474-1489 and again in 1495, over Zakroczym since 1484, over Nur since 1488 and over Warsaw since 1489.
Danutė of Lithuania, was a Lithuanian princess of the Gediminid dynasty and by marriage Duchess of Warsaw.
Bolesław IV of Warsaw, was a Polish prince and member of the House of Piast in the Masovian branch. He was Duke of Warsaw during 1429–1454 and sovereign Duke of Podlachia in 1440–1444.
Bolesław II of Masovia or Bolesław II of Płock, was a Polish prince, member of the House of Piast, Duke of Masovia during 1262-1275 jointly with his brother, after 1275 sole ruler over Płock, after 1294 ruler over all Masovia and Duke of Kraków and Sandomierz during 1288-1289. In 1310 he gave to his sons the districts of Warsaw and Czersk. Also High duke of Poland twice.
Konrad II of Czersk, was a Polish prince member of the House of Piast, Duke of Masovia during 1264-1275 jointly with his brother, after 1275 sole ruler over Czersk and Duke of Sandomierz during 1289.
Trojden I was a Polish prince, Duke of Czersk from 1310, ruler over Warsaw and Liw from 1313, and regent of Płock in the years 1336–1340. He was a member of the House of Piast.
The Duchy of Płock was a feudal district duchy in Masovia, centered on the Płock Land. Its capital was Płock. It existed in the High Middle Ages era, from 1275 to 1294, from 1310 to 1351, and from 1381 to 1462.
Konrad Januszowic, was a Polish prince member of the House of Piast.
Bolesław Januszowic, was a Polish prince member of the House of Piast.
Bolesław V of Warsaw, was a Polish prince member of the House of Piast in the Masovian branch. He was a Duke of Czersk, Liw, Warsaw, Nur, Łomża, Ciechanów, Różan, Zakroczym and Wyszogród during 1454-1471 jointly with his brothers, Duke of Płock, Wizna, Płońsk and Zawkrze during 1462-1471, and after the division of the paternal domains in 1471, sole ruler over Warsaw, Nur and Liw. In 1484 he abdicated his rule over Błonie, Tarczyn, Kamieniec and Zakroczym.
Catherine of Masovia was a Polish princess member of the House of Piast in the Masovian branch.
Casimir I of Warsaw, was a Polish prince, member of the House of Piast, Duke of Czersk 1341-1349 jointly with his brother, after 1345 ruler over Rawa Mazowiecka jointly with his brother, after 1349 sole ruler over Warsaw, after 1351 sole ruler over Sochaczew, Polish vassal since 1351.
Barbara Aleksandrówna was a princess and wife of prince Bolesław IV of Warsaw. She was the daughter of Alexander Włodzimierzowic, Grand Prince of Kiev.
Duchy of Wizna was a district principality and a fiefdom within the United Kingdom of Poland, and later the Crown of the Kingdom of Poland. The country was located in Wizna Land with Wizna as its capital and during its existence it remained in the personal union with the Duchy of Płock. It was formed in 1345 from the part of Duchy of Rawa and was ruled by Bolesław III of Płock. On 18 September 1381 it was incorporated into United Kingdom of Poland. It was reestablished in December 1381 from the part of the Duchy of Masovia under Siemowit IV rule. On 2 December 1382 its territory was pladged to the State of the Teutonic Order. It was again re-established in 1435, when it was given to Władysław I of Płock, ruler of the Duchy of Płock, existed until 1495 when it was incorporated into the Crown of the Kingdom of Poland.
The Duchy of Czersk was a feudal district duchy in Masovia, centered on the Czersk Land. Its capital was Czersk.
The Duchy of Rawa was a feudal district duchy in Masovia, centered on the Rawa Land. Its capital was Rawa. It existed during the High Middle Ages era, from 1313 to 1370, and from 1381 to 1442.
Coat of arms of the Duchy of Czersk is a legendary creature in folklore of Masovia in Poland, that is depicted as a Slavic dragon or wyvern. It was used in the coat of arms of the Masovian Piast dynasty, most notably in the coat of arms of the Duchy of Czersk and the Duchy of Warsaw, where it was depicted respectively as a green and red dragon with red tongue and claws.
