The most densely populated areas are around the valley of the river Ebro , particularly around Zaragoza , and in the Pyrenean foothills , while the areas with the fewest inhabitants tend to be those that are higher up in the Pyrenean mountains , and in most of the southern province of Teruеl .
The most densely populated areas are around the valley of the Ebro river , particularly around Zaragoza , and in the Pyrenean s ( the hills at the base of the Pyrenees ) , while the areas with the fewest inhabitants tend to be those that are higher up in the Pyrenean mountains , and in most of the southern province of Teruel .