The Chronicæ Polanorum add his mother's name, stating "hospitii domestici Pazt filius Chostconis et uxor eius Repca" but ... this contradicts the Annales Polanorum which state that Repka was Piast's wife. Dzieciol highlights a "plausible theory" that Piast was maior domus in the palace of the Popiel rulers before seizing power, although there is no evidence of this in the chronicles. 1
Piast married Repka.
1 Foundation for Medieval Genealogy, Medlands: Origins, Princes of Poland 966-1024.