sentences:  The fragmentation of the duchy continued after Wenceslaus' death in 1468, when in 1474 his sons Casimir II and Wenceslaus II as well as Jan V and Władysław again divided the Zator territory in two along the Skawa river.After the death of Casimir II in 1490 however both parts of the duchy were reunited, and in 1494 Jan V as the last surviving brother became its sole ruler.As Jan himself had no heirs, he decided in the same year to sell the duchy to King John I Albert of Poland, under a guarantee that he would remain duke until his death.