History of Poland during the Piast dynasty of Lesser Poland, the country of the Vistulans, and of Silesia (both taken by Mieszko from the Czech state during the later part of the 10th century), Mieszko's state reached its mature form, including the main regions regarded as ethnically Polish. The Piast lands totaled about in area, with an approximate population of under one million. Initially a pagan, Mieszko I was the first ruler of the Polans tribal union known from contemporary written sources. A detailed account of aspects of Mieszko's early reign was given by Ibrâhîm ibn Ya`qûb, a Jewish traveler, according to whom Mieszko was one of
Mieszko Kazimierzowic no mention of Mieszko's influence on Polish politics. Mieszko died on 28 January 1065. Year of death was noted by "Rocznik kapituły krakowskiej", while day by "Necrologium monasterii superioris Ratisbonensis". He died unmarried and childless. Mieszko Kazimierzowic Mieszko Kazimierzowic ("Kazimierzowic" means "son of Kazimierz") (16 April 1045 – 28 January 1065) was a Polish prince member of the House of Piast. According to some scholars, he was probably Duke of Kuyavia since 1058 until his death. He was the third son of Casimir I the Restorer by his wife Maria Dobroniega, daughter of Vladimir the Great, Grand Duke of Kiev.