Mieszko I of Poland elders, and limited their authority. Clergy who arrived in the country contributed to the development of education and culture, and of the state administration and diplomacy, as well. At the end of Mieszko's reign (ca. 990), Poland began to pay tribute to the pope (Peter's Pence). However, the conversion of the Polish population to Catholicism was a long-term process, and was not completed during the reign of Mieszko I. The duke probably had to deal with rebellions led by the old pagan priest caste. In some villages, the old Slavic beliefs and customs were continued until the 16th century. After
Mieszko I of Poland with the Polish-German war, or the expectation of such. The duration of the expedition suggests that it may have reached as far east as the vicinity of Poznań. The Polish-German agreement was concluded in the spring or possibly summer of 980, because in November of that year Otto II left his country and went to Italy. It appears that during this time Mieszko I married Oda, daughter of Dietrich of Haldensleben, Margrave of the Northern March, after abducting her from the monastery of Kalbe. Chronicler Thietmar described the event as follows: Although Thietmar made no mention of warfare that possibly