sentences:  These buildings show the peak and the importance that this "comarca" had during those centuries.From the 11th century on, a special, perhaps unique, human habitat began to form in the highest parts of these valleys.Its economy was based on ancient transhumant cattle breeding practices which may have been traditional to more extensive areas of Europe and the region, but which with time only survived in isolated places such as these valleys, and others elsewhere in Europe, and in Asia and Africa.