Thietmar of Merseburg
The settlement on the road leading from Magdeburg to Gniezno was first mentioned as "Mezerici" by the medieval chronicler Thietmar of Merseburg in the course of the 1005 campaign of King Henry II of Germany into the Polish lands of Duke Bolesław I Chrobry. The Old Polish name "Mezyriecze" first appeared in the 1112/16 "Gesta principum Polonorum" by Gallus Anonymus.