History of Poland during the Piast dynasty
The period of rule by the Piast dynasty between the 10th and 14th centuries is the first major stage of the history of the Polish state. The dynasty was founded by a series of dukes listed by the chronicler Gall Anonymous in the early 12th century: Siemowit, Lestek and Siemomysł. It was Mieszko I, the son of Siemomysł, who is considered the founder of the Polish state. Mieszko converted to Christianity of the Western Latin Church in an event known as the Baptism of Poland in 966. His acceptance of Christianity marked the formal beginning of Polish statehood, which was recognized by the Papacy and other Christian states of Europe. The Papal incipit titled Dagome iudex, first defined Poland's geographical boundaries and affirmed that Mieszko was under the protection of the Apostolic See. Mieszko also completed a unification of the Lechitic tribal lands that was fundamental to the existence of the new country of Poland. The ruling house then remained in power in the Polish lands until 1370.
Following the emergence of the Polish state, a series of rulers converted the population to Christianity, created a kingdom of Poland in 1025 and integrated Poland into the prevailing culture of Europe. Mieszko's son Bolesław I the Brave established a Roman Catholic Archdiocese in Gniezno, pursued territorial conquests and was officially crowned in 1025 as the first king of Poland. The first Piast monarchy collapsed with the death of Mieszko II Lambert in 1034, followed by its restoration under Casimir I in 1042. In the process, the royal dignity for Polish rulers was forfeited, and the state reverted to the status of a duchy. Duke Casimir's son Bolesław II the Bold revived the military assertiveness of Bolesław I, but became fatally involved in a conflict with Bishop Stanislaus of Szczepanów and was expelled from the country.
Bolesław III, the last duke of the early period, succeeded in defending his country and recovering territories previously lost. Upon his death in 1138, Poland was divided among his sons. The resulting internal fragmentation eroded the initial Piast monarchical structure in the 12th and 13th centuries and caused fundamental and lasting changes.
Konrad I of Masovia invited the Teutonic Knights to help him fight the Baltic Prussian pagans, which led to centuries of Poland's warfare with the Knights and the German Prussian state.
In 1320, the kingdom was restored under Władysław I the Elbow-high, then strengthened and expanded by his son Casimir III the Great. The western provinces of Silesia and Pomerania were lost after the fragmentation, and Poland began expanding to the east. The period ended with the reigns of two members of the Capetian House of Anjou between 1370 and 1384. The consolidation in the 14th century laid the base for the new powerful kingdom of Poland that was to follow.
10th–12th century
Mieszko I and the adoption of Christianity in Poland (ca. 960–992)
The tribe of the Polans in what is now Greater Poland gave rise to a tribal predecessor of the Polish state in the early part of the 10th century, with the Polans settling in the flatlands around the emerging strongholds of Giecz, Poznań, Gniezno and Ostrów Lednicki. Accelerated rebuilding of old tribal fortified settlements, construction of massive new ones and territorial expansion took place during the period –950. The Polish state developed from these tribal roots in the second half of the century. According to the 12th-century chronicler Gallus Anonymus, the Polans were ruled at this time by the Piast dynasty. In existing sources from the 10th century, Piast ruler Mieszko I was first mentioned by Widukind of Corvey in his Res gestae saxonicae, a chronicle of events in Germany. Widukind reported that Mieszko's forces were twice defeated in 963 by the Veleti tribes acting in cooperation with the Saxon exile Wichmann the Younger. Under Mieszko's rule, his tribal state accepted Christianity and became the Polish state.The viability of the Mieszko's emerging state was assured by the persistent territorial expansion of the early Piast rulers. Beginning with a very small area around Gniezno, the Piast expansion lasted throughout most of the 10th century and resulted in a territory approximating that of present-day Poland. The Polanie tribe conquered and merged with other Slavic tribes and first formed a tribal federation, then later a centralized state. After the addition of Lesser Poland, the country of the Vistulans, and of Silesia, Mieszko's state reached its mature form, including the main regions regarded as ethnically Polish. The Piast lands totaled about in area, with an approximate population of under one million.
File:Grody w okresie Mieszka I.png|thumb|left|250px|Expansion of the Polans territory under the Piast dynasty in the 10th century
Initially a pagan, Mieszko I was the first ruler of the Polans tribal union known from contemporary written sources. A detailed account of aspects of Mieszko's early reign was given by Ibrâhîm ibn Ya`qûb, a Jewish traveler, according to whom Mieszko was one of four Slavic "kings" established in central and southern Europe in the 960s. In 965, Mieszko, who was allied with Boleslaus I, Duke of Bohemia at the time, married the duke's daughter Doubravka, a Christian princess. Mieszko's conversion to Latin Christianity followed on 14 April 966, an event known as the Baptism of Poland that is considered to be the founding event of the Polish state. In the aftermath of Mieszko's victory over a force of the Velunzani in 967, which was led by Wichmann, the first missionary bishop was appointed: Jordan, bishop of Poland. The action counteracted the intended eastern expansion of the Magdeburg Archdiocese, which was established at about the same time.
Mieszko's state had a complex political relationship with the German Holy Roman Empire, as Mieszko was a "friend", ally and vassal of Holy Roman Emperor Otto I and paid him tribute from the western part of his lands. Mieszko fought wars with the Polabian Slavs, the Czechs, Margrave Gero of the Saxon Eastern March in 963–964 and Margrave Odo I of the Saxon Eastern March in 972 in the Battle of Cedynia. The victories over Wichmann and Odo allowed Mieszko to extend his Pomeranian possessions west to the vicinity of the Oder River and its mouth. After the death of Otto I, and then again after the death of Holy Roman Emperor Otto II, Mieszko supported Henry the Quarrelsome, a pretender to the imperial crown. After the death of Doubravka in 977, Mieszko married Oda von Haldensleben, daughter of Dietrich, Margrave of the Northern March, ca. 980. When fighting the Czechs in 990, Mieszko was helped by the Holy Roman Empire. By about the year 990, when Mieszko I officially submitted his country to the authority of the Holy See, he had transformed Poland into one of the strongest powers in central-eastern Europe.
The reign of Bolesław I and establishment of a Kingdom of Poland (992–1025)
One of the most important concerns of Bolesław's early reign was building up the Polish church. Bolesław cultivated Adalbert of Prague of the Slavník family, a well-connected Czech bishop in exile and missionary who was killed in 997 while on a mission in Prussia. Bolesław skillfully took advantage of his death: his martyrdom led to his elevation as patron saint of Poland and resulted in the creation of an independent Polish province of the Church with Radim Gaudentius as Archbishop of Gniezno. In the year 1000, the young Emperor Otto III came as a pilgrim to visit St. Adalbert's grave and lent his support to Bolesław during the Congress of Gniezno; the Gniezno Archdiocese and several subordinate dioceses were established on this occasion. The Polish ecclesiastical province effectively served as an essential anchor and an institution to fall back on for the Piast state, helping it to survive in the troubled centuries ahead.Bolesław at first chose to continue his father's policy of cooperation with the Holy Roman Empire but when Emperor Otto III died in 1002, Bolesław's relationship with his successor Henry II turned out to be much more difficult, and it resulted in a series of wars. From 1003 to 1004, Bolesław intervened militarily in Czech dynastic conflicts. After his forces were removed from Bohemia in 1018, Bolesław retained Moravia. In 1013, the marriage between Bolesław's son Mieszko and Richeza of Lotharingia, the niece of Emperor Otto III and future mother of Casimir I the Restorer, took place. The conflicts with Germany ended in 1018 with the Peace of Bautzen on favorable terms for Bolesław. In the context of the 1018 Kiev expedition, Bolesław took over the western part of Red Ruthenia. In 1025, shortly before his death, Bolesław I finally succeeded in obtaining the papal permission to crown himself, and he became the first king of Poland.
Bolesław's expansionist policies were costly to the Polish state and were not always successful. He lost, for example, the economically crucial Farther Pomerania in 1005 together with its new bishopric in Kołobrzeg; the region had previously been conquered with great effort by Mieszko.