Mieszko II Lambert by the chronicles of Gottfried of Viterbo, refers to Bezprym. However, the historians now think that he was killed in a plot hatched by the aristocracy. He was buried in the Cathedral of St. Peter and St. Paul. After Mieszko II's death, Poland's peasants revolted in a "pagan reaction." The exact reasons and date are unknown. Mieszko II's only son and heir, Casimir I, was either expelled by this insurrection, or the insurrection was caused by the aristocracy's expulsion of him. Some modern historians argue that the insurrection was caused more by economic than by religious issues, such as new
Mieszko I, Duke of Cieszyn The Obituary of the Church of St. Vincent in Wrocław showed the existence of a certain "Grzymisława, Duchess of Opole" ("Grimizlaua ducissa Opuliensis") who was buried there around 13 September 1286. Her parentage is also unknown, but her name suggests a Russian origin, probably member of the Rurikids. Her title suggests that she may have been the wife of Mieszko I or the first wife of Bolko I (Mieszko I's brother), or maybe a completely different person. Also, the exact date of their marriage was uncertain, but after a further reconstructions of their children's birth dates, was placed between 1275