The realm of Duke Mieszko I found itself in a difficult situation in the 960s. Active political development and expansion of power necessitated a choice between joining the political mainstream of contemporary Europe by accepting baptism or being swept away by the new political and economic currents pressing in from all sides and by military expansion from the west. Adopting Christianity, which guaranteed the modernisation of the country, became the basic precondition to achieving these aims.

Given the prevailing political realities, introducing Christianity obviated a lot of serious problems and strengthened the power of the duke while simultaneously throwing him in the deep end of European politics. This was accomplished through the marriage of Mieszko I to the Bohemian princess Dobrawa. The place where Mieszko I was baptised in 966 remains unknown. The ceremony may have been held at Ostrów Lednicki, Gniezno, Poznań or even Ratyzbona (modern Regensburg, Germany). The first missionary bishopric was established in Poznań in 968 and placed under the direction of Jordan. The remains of the martyr St. Wojciech (often referred to as St. Adalbert of Prague in English) were laid to rest in Gniezno Cathedral in 999. The first archbishopric was created in Gniezno a year later and Gniezno Cathedral soon became the coronation cathedral for the kings of Poland.