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
Bolesław I the Brave Mieszko II) that gave the King his widely known nickname of "Brave" (Polish: "Chrobry") -later Gallus Anonymus in the Chapter 6 of his "Gesta principum Polonorum" named the Polish ruler as "Bolezlavus qui dicebatur Gloriosus seu Chrabri". The contemporaneous Thietmar of Merseburg recorded Bolesław's marriages, also mentioning his children. Bolesław's first wife was an unnamed daughter of Rikdag, Margrave of Meissen. Historian Manteuffel says that the marriage was arranged in the early 980s by Mieszko I who wanted to strengthen his links with the Saxon lords and to enable his son to succeed Rikdag in Meissen. Bolesław "later sent her