Płock in the context of "Masovian Voivodeship"

The Vistula (/ˈvɪstjʊlə/; Polish: Wisła [ˈviswa] ) is the longest river in Poland and the ninth-longest in Europe, at 1,047 kilometres (651 miles) in length. Its drainage basin, extending into three other countries apart from Poland, covers 193,960 km (74,890 sq mi), of which 168,868 km (65,200 sq mi) is in Poland.

The Vistula rises at Barania Góra in the south of Poland, 1,220 meters (4,000 ft) above sea level in the Silesian Beskids (western part of Carpathian Mountains), where it begins with the White Little Vistula (Biała Wisełka) and the Black Little Vistula (Czarna Wisełka). It flows through Poland's largest cities, including Kraków, Sandomierz, Warsaw, Płock, Włocławek, Toruń, Bydgoszcz, Świecie, Grudziądz, Tczew and Gdańsk. It empties into the Vistula Lagoon (Zalew Wiślany) or directly into the Gdańsk Bay of the Baltic Sea with a delta of six main branches (Leniwka, Przekop, Śmiała Wisła, Martwa Wisła, Nogat and Szkarpawa).

Bolesław II of Masovia or Bolesław II of Płock (pl: Bolesław II mazowiecki (płocki); ca. 1253/58 – 20 April 1313), 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 (1288, 1289).

Mazovia or Masovia (Polish: Mazowsze [maˈzɔfʂɛ] ) is a historical region in mid-north-eastern Poland. It spans the North European Plain, roughly between Łódź and Białystok, with Warsaw being the largest city and Płock being the capital of the region. Throughout the centuries, Mazovia developed a separate sub-culture featuring diverse folk songs, architecture, dress and traditions different from those of other Poles.

Historical Mazovia existed from the Middle Ages until the partitions of Poland and consisted of three voivodeships with the capitals in Warsaw, Płock and Rawa. The main city of the region was Płock, which was even capital of Poland from 1079 to 1138; however, in Early Modern Times Płock lost its importance to Warsaw, which became the capital of Poland. From 1138, Mazovia was governed by a separate branch of the Piast dynasty and when the last ruler of the independent Duchy of Mazovia died, it was fully incorporated to the Polish Crown in 1526. During the Polish–Lithuanian Commonwealth over 20% of Mazovian population was categorized as petty nobility. Between 1816 and 1844, the Mazovian Governorate was established, which encompassed the south of the region along with Łęczyca Land and south-eastern Kuyavia. The former inhabitants of Mazovia are the Masurians, who since the Late Middle Ages settled in neighboring southern Prussia, a region later called Masuria, where they converted to Protestantism in the Reformation era, thus leaving Catholicism, to which their relatives from Mazovia still adhered.

In the history of Poland, a royal city or royal town (Polish: miasto królewskie) was an urban settlement within the crown lands (Polish: królewszczyzna).

The most influential royal cities enjoyed voting rights during the free election period in Poland (1572–1791). These cities were Gdańsk, Warsaw, Kraków, Poznań, Lwów, Wilno, Toruń, Lublin, Kamieniec and Elbląg. Other important royal cities included Gniezno (ecclesiastical capital of Poland and former capital of early medieval Poland), Płock (former capital of medieval Poland), Piotrków (second most important political center of Poland in the early and mid-16th century as the main location of the Sejm, and then the main Crown Tribunal location alongside Lublin, thus one of the two judiciary capitals of Poland), Grodno (de facto capital of the Polish–Lithuanian Commonwealth in the 1580s and then the general sejm location alongside Warsaw), Bydgoszcz and Kalisz (temporary locations of the Crown Tribunal), and Sandomierz, Przemyśl, Kazimierz.

Siemowit IV (Ziemowit IV), also known as Siemowit IV the Younger (pl: Siemowit IV Młodszy; ca. 1353/1356 – 21 January 1426), was a Polish prince, member of the Masovian branch of the House of Piast and from 1373 or 1374 Duke of Rawa, and after the division of the paternal inheritance between him and his brother in 1381, ruler over Rawa, Płock, Sochaczew, Gostynin, Płońsk and Wizna, after 1386 hereditary Polish vassal, after 1388 ruler over Belz. During 1382–1401 he lost Wizna and during 1384–1399 and 1407–1411 he lost Zawkrze, during 1384–1399 he lost Płońsk, which was taken by the Teutonic Order.

He was the second son of Siemowit III, Duke of Masovia and his first wife Euphemia, daughter of Nicholas II of Opava.

The 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.