Poland to form into a recognizable unitary and territorial entity around the middle of the 10th century under the Piast dynasty. Poland's first historically documented ruler, Mieszko I, accepted Christianity with the Baptism of Poland in 966, as the new official religion of his subjects. The bulk of the population converted in the course of the next few centuries. In 1000, Boleslaw the Brave, continuing the policy of his father Mieszko, held a Congress of Gniezno and created the metropolis of Gniezno and the dioceses of Kraków, Kołobrzeg, and Wrocław. However, the pagan unrest led to the transfer of the capital
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,