Were these walls built by early settlers and shepherds to mark property boundaries or are they pre European in origin?

A network of stone wall sections  follow the ridgelines and gullies linking the rocky north facing foothills to the plains below. They have been noted from Faithfuls Creek to Burnt Creek and are most extensive around Longwood East. The building style of each structure is unique, displaying various skill levels  . Some walls are low rubble piles , others higher, many link large boulders and there are often very heavy rocks incorporated into the stonework. These walls are not continuous but many sections stretch over 150m without a break.

Have you noticed these very old walls on you property or heard stories of where they occur?

Can anyone offer explanations as to their origin?