Mieszko I of Poland death occurred from causes other than natural. According to Thietmar the Polish ruler died "in an old age, overcame with fever". Probably he was buried in the Poznań Cathedral. The remains of the first historical ruler of Poland have never been found and the place of his burial is not known with certainty. In 1836–1837 a cenotaph was built for Mieszko I and his successor Bolesław I the Brave in the Golden Chapel () at the Poznań Cathedral, where the damaged remains found in the 14th century tomb of Bolesław were placed. According to Thietmar Mieszko I divided his state
Mieszko I of Poland poses some problems of interpretation of the information regarding the attack of Margrave Gero on the Slavic tribes, as a result of which he purportedly "subordinated to the authority of the Emperor Lusatia and the Selpuli" (meaning the Słupian tribes) "and also Mieszko with his subjects". According to the majority of modern historians, Thietmar made an error summarizing the chronicle of Widukind, placing the Gero raid there instead of the fighting that Mieszko conducted at that time against Wichmann the Younger. Other sources make no mention of such conquest and of putting the Polans state on the same footing with