The territory of Fordongianus does not provide any particular evidence on life prior to the Roman Era (fig. 1).

Fig. 1 - Indication of the area called Casteddu Becciu, where you have the rests of a nuraghe (from Google Earth; re-worked by C. Tronchetti).

In the sites of Domigheddas and Gularis Santu Juanni there are some small prehistoric burial caves which were found completely empty (figs. 2-3). 

Fig. 2 - Burial cave of Is Domigheddas (link).

Fig. 3 - Burial cave in the territory of Sorradile (link).

To the North-West of today's town you can find the remains of a nuraghe called on Casteddu Becciu or Ecciu or Ezzu (the old castle), standing on a small plateau which controls the river valley (fig. 4). The nuraghe had two vaulted chambers joined by a corridor and was adapted and restructured at a later date, probably maintaining its function as a guard post. 

Fig. 4  - Nuraghe Madrone (Silanus-NU). The nuraghe stands on a small hill controlling the river (from Lo Schiavo et alii 1990, p. 57).

It is not certain as to when that happened, whether in the Carthage or Roman period, preferable considering the absence of sure Punic evidence in the area.