Mieszko I of Poland mentions a gift or dedication of Mieszko's land to the Pope (the act took place almost a hundred years earlier). It is roughly his borders that Poland was returned to in 1945. There is no certain information on Mieszko I's life before he took control over his lands. Only the "Lesser Poland Chronicle" gives the date of his birth as somewhere between the years 920–931 (depending on the version of the manuscript), however, modern researchers don't recognize the Chronicle as a reliable source. Several historians on the basis of their investigations postulated the date of Mieszko I's birth to have
Mieszko I of Poland Czech language and had to come from Dobrawa's entourage and the church elements that arrived with her. Perhaps with her also came the first Polish bishop, Jordan. It could be that the reason for the Czech preference of Mieszko was the existence in Bohemia of a mission which followed the precepts of the Byzantine Greek brothers and later saints Cyril and Methodius, who developed and performed the liturgy in the Slavic rite, more readily understood by Mieszko and his subjects. The Slavic rite church branch had survived in Bohemia for another hundred years after Mieszko's baptism. Through the adoption of