Kingdom of Poland (1385–1569) in the context of "Czersk Land"

The Jagiellonian (US: /ˌjɑːɡjəˈloʊniən/ YAH-gyə-LOH-nee-ən) or Jagellonian dynasty (US: /ˌjɑːɡəˈ-/ YAH-gə-; Lithuanian: Jogailaičių dinastija; Polish: dynastia jagiellońska), otherwise the Jagiellon dynasty (Polish: dynastia Jagiellonów), the House of Jagiellon (Polish: Dom Jagiellonów), or simply the Jagiellons (Lithuanian: Jogailaičiai; Polish: Jagiellonowie; Latin: Iagellonidae), was the name assumed by a cadet branch of the Lithuanian ducal dynasty of Gediminids upon reception by Jogaila, the Grand Duke of Lithuania, of baptism as Ladislaus in 1386, which paved the way to his ensuing marriage to the Queen Regnant Hedwig of Poland, resulting in his ascension to the Crown of the Kingdom of Poland as Ladislaus II Jagiełło (initially ruling jure uxoris jointly with Jadwiga until her death), and the effective promotion of his branch to a royal dynasty. The Jagiellons were polyglots and per historical evidence Casimir IV Jagiellon and his son Saint Casimir possibly were the last Jagiellons who spoke in their patrilineal ancestors' Lithuanian language; however, even the last patrilineal Jagiellonian monarch Sigismund II Augustus maintained two separate and equally lavish Lithuanian-speaking and Polish-speaking royal courts in Lithuania's capital Vilnius. The Jagiellons reigned in several European countries between the 14th and 16th centuries. Members of the dynasty were Kings of Poland (1386–1572), Grand Dukes of Lithuania (1377–1392 and 1440–1572), Kings of Hungary (1440–1444 and 1490–1526), and Kings of Bohemia and imperial electors (1471–1526).

The personal union between the Kingdom of Poland and the Grand Duchy of Lithuania (converted in 1569 with the Treaty of Lublin into the Polish–Lithuanian Commonwealth) is the reason for the common appellation "Poland–Lithuania" in discussions about the area from the Late Middle Ages onward. One Jagiellon, Ladislaus III of Poland, briefly ruled both Poland and Hungary (1440–1444), and two others ruled both Bohemia and Hungary (1490–1526) and then continued in the distaff line as a branch of the House of Habsburg.

Golden Liberty (Latin: Aurea Libertas; Polish: Złota Wolność [ˈzwɔ.ta ˈvɔl.nɔɕt͡ɕ], Lithuanian: Auksinė laisvė), sometimes referred to as Golden Freedoms, Nobles' Democracy or Nobles' Commonwealth (Polish: Rzeczpospolita Szlachecka or Złota wolność szlachecka) was a political system in the Kingdom of Poland and, after the Union of Lublin (1569), in the Polish–Lithuanian Commonwealth. Under that system, all nobles (szlachta), regardless of rank, economic status or their ethnic background were considered to have equal legal status and enjoyed extensive legal rights and privileges. The nobility controlled the legislature (the Sejm—the parliament) and the Commonwealth's elected king.

Red Ruthenia, also called Red Rus' or Red Russia, is a term used since the Middle Ages for the south-western principalities of Kievan Rus', namely the Principality of Peremyshl and the Principality of Belz. It is closely related to the term Cherven Cities ("Red Cities").

First mentioned by that name in a Polish chronicle of 1321, Red Ruthenia was the portion of Ruthenia incorporated into Poland by Casimir the Great during the 14th century. Following the Mongol invasion of Kievan Rus' in the 13th century, Red Ruthenia was contested by the Grand Duchy of Lithuania (the Gediminids), the Kingdom of Poland (the Piasts), the Kingdom of Hungary and the Kingdom of Galicia–Volhynia. After the Galicia–Volhynia Wars, for about 400 years, most of Red Ruthenia became part of Poland as the Ruthenian Voivodeship.

The monarchs of Prussia were members of the House of Hohenzollern who were the hereditary rulers of the former German state of Prussia from its founding in 1525 as the Duchy of Prussia. The Duchy had evolved out of the Teutonic Order, a Roman Catholic crusader state and theocracy located along the eastern coast of the Baltic Sea. The Teutonic Knights were under the leadership of a Grand Master, the last of whom, Albert, converted to Protestantism and secularized the lands, which then became the Duchy of Prussia.

The Duchy was initially a vassal of the Kingdom of Poland, as a result of the terms of the Prussian Homage whereby Albert was granted the Duchy as part of the terms of peace following the Prussian War. When the main line of Prussian Hohenzollerns died out in 1618, the Duchy passed to a different branch of the family, who also reigned as Electors of Brandenburg in the Holy Roman Empire. While still nominally two different territories, Prussia under the suzerainty of Poland and Brandenburg under the suzerainty of the Holy Roman Empire, the two states are known together historiographically as Brandenburg-Prussia.

The Council of Constance (Latin: Concilium Constantiense; German: Konzil von Konstanz) was an ecumenical council of the Catholic Church that was held from 1414 to 1418 in the Bishopric of Constance (Konstanz) in present-day Germany. This was the first ecumenical council convened in the Holy Roman Empire. The council ended the Western Schism by deposing or accepting the resignation of the remaining papal claimants and by electing Pope Martin V. It was the last papal election to take place outside of Italy.

The council also condemned Jan Hus as a heretic and facilitated his execution; and it ruled on issues of national sovereignty and the rights of pagans and just war in response to a conflict between the Grand Duchy of Lithuania, the Kingdom of Poland and the Order of the Teutonic Knights.

The House of Gediminas (Lithuanian: Gediminaičių dinastija), or simply the Gediminids, were a dynasty of monarchs in the Grand Duchy of Lithuania that reigned from the 14th to the 16th century. A cadet branch of this family, known as the Jagiellonian dynasty, reigned also in the Kingdom of Poland, Kingdom of Hungary and Kingdom of Bohemia. Several other branches ranked among the leading aristocratic dynasties of Poland and Russia into recent times.

Gediminas' Cap was used during the inaugurations of Gediminids as Lithuanian monarchs in the Vilnius Cathedral and symbolized the dynasty's continuity.

Bona Sforza (2 February 1494 – 19 November 1557) was Queen of Poland and Grand Duchess of Lithuania as the second wife of Sigismund the Old, and Duchess of Bari and Rossano by her own right. She was a surviving member of the powerful House of Sforza, which had ruled the Duchy of Milan since 1450.

Smart, energetic and ambitious, Bona became heavily involved in the political and cultural life of the Polish–Lithuanian union. To increase state revenue during the Chicken War, she implemented various economic and agricultural reforms, including the far-reaching Wallach Reform in the Grand Duchy of Lithuania. In foreign policy, she allied with the Ottoman Empire and sometimes opposed the Habsburgs. Her descendants became beneficiaries of the Neapolitan sums, a loan to Philip II of Spain that was never completely paid.