One of the most important Sardinian Neo-enolithic sites stands on the small hill of Biru 'e Concas, in the locality of Coa sa Mandara, at Sorgono (Nu). This extraordinary concentration of aniconic menhirs, proto-anthropomorphic and statue-menhirs constitutes part of a vast settlement on which excavations took place in 1994. It is not possible to calculate the exact number of menhirs as some are buried and others piled up where they have been removed from the terrain by local farmers, however there are over 120 examples. The site has been compromised by agricultural activity and this has created problems in the understanding of the function of the megalithic complex. In 2011, a wall was found on a slight slope on the eastern side, which it is suggested delimited a sacred area or settlement. The first excavations on the site were undertaken in 1994 as part of a vast programme of exploration in the entire area, financed by the Comunità Montana 12 Barbagia Mandrolisai. In 2004, the local GAL funded a project for further excavations and the enhancement of the site. Both operations were coordinated by the Archaeological Superintendency of Sassari and Nuoro and directed by Dr. M.A. Fadda. The investigations undertaken during this campaign aimed to make a first census of the menhirs and dig a series of trenches in various parts of the middle-low zone of the hill and the valley floor. The pottery finds, characterised by incised parallel lines, notches or “small leaves”, date to the Copper Age, in particular the period of the Monte Claro culture (Late Eneolithic), the settlement’s most representative phase.

In 2004, excavations took place in the two areas with the greatest concentration of menhirs. In area 1, the monoliths were concentrated in a space of about 220 m2, positioned above the ground surface or slightly buried and lying on the ground without any apparent order. The removal of the vegetation and humus revealed 35 monoliths of different sizes and type. Aniconic and proto-anthropomorphic examples with convex plane section were predominant. Two statue-menhirs showed lines suggesting a human face, in one case represented by two cup-marks forming the eyes and a rectilinear appendage for the nose. The other presents a stylized representation of the nose and eyes and a small dagger at the waist, elements typical of the examples found in the Sarcidano area. Area 2 is situated on the hill’s east slope. The group of 32 aniconic and proto-anthropomorphic monoliths, all knocked over, are partly arranged in an alignment of two rows, the stones resting on a thin earth deposit and on the outcropping rock, while the upper part of the group lies in a disorganised state with menhirs amassed one on top of the other and partially buried. Once the secondary deposition of the menhirs had been established some of the stones were replaced in an upright position forming two rows in order to render them visible and to enhance the area.