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 took place on this occasion, the information on the return of the accord, acting for the good of the country and release of prisoners indicate that a conflict actually did occur. The marriage with Oda considerably affected the position and prestige of Mieszko, who entered the world of Saxon aristocracy. As a son-in-law of Margrave Dietrich, he gained an ally in one of the most influential politicians of the Holy Roman Empire. As the Margrave was a distant relative of the Emperor, Mieszko became a member of the circle connected to the imperial ruling house. Probably in the early 980s