Casimir I the Restorer in the context of History of Poland (966–1385)

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 II the Bold (Polish: Bolesław II Śmiały; c. 1042 – 2 or 3 April 1081 or 1082), also known as the Generous (Szczodry Polish), was Duke of Poland from 1058 to 1076 and King of Poland from 1076 to 1079. He was the eldest son of Duke Casimir I the Restorer and Maria Dobroniega of Kiev.

Bolesław II is considered to have been one of the most capable of the Piast rulers. In 1075 he re-established the Archdiocese of Gniezno (consecrated in 1064) and founded the Diocese of Płock. He established Benedictine monasteries in Mogilno, Lubin and Wrocław. Bolesław II was also the first Polish monarch to produce his own coinage in quantity great enough to replace the foreign coins prevalent in the country during the reigns of the first Piast kings. He established royal mints in Kraków and Wrocław and reformed the coinage, which brought considerable revenue into the royal coffers. All these efforts had an enormous influence on the economic and cultural development of the country.