Polydorus was the youngest and only male child of Cadmus and Harmonia,[1] his sisters were Autonoë, Ino, Agave and Semele.
Last of all Harmonia added a little son to the brood of sisters, and made Cadmos happy – Polydoros, the morning star of the Aonian nation, younger than rosy cheek Semele.
[6] When their son Labdacus was still young, Polydorus died of unknown causes, entrusting his father-in-law Nycteus to care the infant prince and to be his regent.
[7] In Pausanias's history, Polydorus' rule began when his father abdicated the throne and together with his mother Harmonia migrated to the Illyrian tribe of the Enchelii, but this is the only source for such a timeline.
[9] A different account by Diodorus stated that the Thebans were exiled a second time (the first time during the reign of Cadmus) for Polydorus came back and was dissatisfied with the situation because of the misfortunes that had befallen Amphion, the previous king,[10] in connection with his children.