In the south the lower Po River (Polesine) formed the border with the Papal States. The Terraferma comprised the western and central parts of the historic Friuli region, except for the easternmost part along the Isonzo River, which was held by the Imperial Counts of Görz. In the north, the Carnic and Julian Alps marked the border with the Inner Austrian duchies of Carinthia and Carniola.