Mieszko II Lambert the help of foreign forces. Probably the brother who caused the first problems to Mieszko II was Bezprym, who allegedly with the support of Otto won the alliance of Kiev in order to take power. When Mieszko II was busy defending Lusatia from the troops of Conrad II, the Kievan expedition started from the east with Yaroslav I the Wise as the leader. In 1031 Poland was invaded and then Bezprym was settled on the throne. Mieszko II and his family were forced to flee the country. Queen Richeza and her children found refuge in Germany. The King couldn't escape
Mieszko I of Poland from the second part of the name *Dago-mierz, since the merger in pronunciation of "sz" with the devoiced "rz" which would appear in this position is quite recent. However, some historians believe that the word "Dagome" is a melding of two names: the Roman Catholic "Dago," for "Dagobert" (Mieszko's hypothetical baptismal name), and the Slavic "Me," for "Mieszko." The Latin word "iudex" ("judge") would be used in the meaning of "prince." Another interpretation is that "Dagome iudex" is a corruption of "Ego Mesco dux" ("I, Prince Mieszko"). Mieszko I took over the tribal rule after his father's death ca. 950–960,