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 III the Old several foreign policy successes through his daughter's marriages: Elisabeth about 1173 married Duke Soběslav II of Bohemia and through the dynastic arrangement between his daughter Anastasia and the Griffin duke Bogislaw I of Pomerania, Mieszko once again reinforced Polish sovereignty over the Pomeranian duchy. In 1177 Mieszko's first-born son Odon, fearing for his inheritance, rebelled against his father. He was supported by Bishop Gedko of Kraków, his cousin Bolesław the Tall and his uncle Casimir the Just. For Odon, the main reason of his rebellion was the favoritism of Mieszko to the offspring of his second marriage and the attempts