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 expanding and improving the so-called war monarchy system. According to existing sources, Mieszko I was a wise politician, a talented military leader, and a charismatic ruler. He successfully used diplomacy, concluding alliances, first with Bohemia, then Sweden, and the Holy Roman Empire. In foreign policy, he placed the interests of his country foremost, even entering into agreements with his former enemies. On his death, he left to his sons a country with greatly expanded territories, and a well-established position in Europe. Mieszko I also enigmatically appeared as "Dagome" in a papal document dating to about 1085, called "Dagome iudex", which