Question: What is the date of death of Henry Of Sandomierz's father?
Sentence (from "Bolesław III Wrymouth"): Bolesław, like Bolesław II the Generous, based his foreign policy on maintaining good relations with neighboring Hungary and Kievan Rus, with whom he forged strong links through marriage and military cooperation in order to break the political dependence on Germany and his vassal, the King of Bohemia, who in moments of weakness of Polish policy was forced to pay tribute in Silesia.
Relevant evidence: No