South of Heidelstein and Hoher Hölle the narrow head of the Brend valley near Bischofsheim forms the boundary with another mountain group of the High Rhön, the Kreuzberg Group, which contains the Arnsberg () and the Kreuzberg (). In between these two mountains lies the source of the Sinn. This river, which forms a wide and deep valley head flanked by the Dammersfeld ridge, flows to the southwest.