 In 1180 large portions west of the Weser were ceded to the Bishops of Cologne, while some central parts between the Weser and the Elbe remained with the Guelphs, becoming later the Duchy of Brunswick-Lüneburg.The remaining eastern lands, together with the title of Duke of Saxony, passed to an Ascanian dynasty (descended from Eilika Billung, Wulfhild's younger sister) and were divided in 1260 into the two small states of Saxe-Lauenburg and Saxe-Wittenberg.The former state was also named "Lower Saxony", the latter "Upper Saxony", thence the later names of the two Imperial Circles Saxe-Lauenburg and Saxe-Wittenberg.