What family lineage was XXX part of?
Casimir I the Restorer
Casimir I the Restorer (Polish: Kazimierz I Odnowiciel; b. Kraków, 25 July 1016 -- d. Poznań, 28 November 1058), was a Duke of Poland of the Piast dynasty and the de jure monarch of the entire country from 1034 until his death.
Piast dynasty