Mieszko I of Poland and half a century later, by Bishop Thietmar of Merseburg. By the time Mieszko I took over from his father, the Polans' tribal federation of Greater Poland had for some time been actively expanding. Continuing this process, perhaps in the first years of Mieszko's reign, if it had not been done already by his father, Mieszko I conquered Masovia. Likely also during that period or earlier, at least partially Gdańsk Pomerania was obtained. Mieszko's interests were then concentrated mainly on areas occupied by the eastern (near the Oder River) branches of the Polabian Slavs; some of them became soon subordinated
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