Two display cases of the Museum are dedicated to the recent excavations of the Nuragic village of Sa Osa led by the Archeological Superintendence of Cagliari and Oristano. The village of Sa Osa was populated for a very long period. Initial phases of settlements date back to the Copper Age (3rd millennium BC), then settlements developed mainly in the Nuragic period, from the Middle Bronze Age (1700-1365 BC) until the Early Iron Age (9th -half of the 8th century BC).
The site is situated on the plain of Campidano Maggiore, about 2 km from the current coastline of the Gulf of Oristano and about 500 m from the right bank of the Tirso River. It also occupies a slight floodplain at 6 m above sea level, which slopes south towards the bottom of the river valley, the so-called Bennaxi. The site is about 200 m from the village of S’Arrieddu, where a settlement of Ozieri facies (4th millennium BC) is located, and a lithic cist grave of the Beaker and Bonnannaro culture (late 3rd-early 2nd millennium BC) was found.
At the moment the only investigated part of the archaeological site of Sa Osa is located in the area of the roundabout that joins the main road Rimedio-Torregrande with the street coming from the new bridge over the Tirso (Brabau locality).
The prehistoric and Nuragic settlement, between the Copper Age and the Middle Bronze Age, is characterized from its earliest phases by ditched enclosures, in which the deposits contained the remains of meals, including animal bones and shellfish, plane and decorated pottery, bone and obsidian tools.
The village built in the next phase of the Late Bronze Age (1365-1200 BC) is characterized by the presence of numerous wells dug into the ground, next to houses in some cases built with stone basements. In one of these wells, about 5 m deep, pottery (shown in the two display cases of the Museum), animal bones, grape and fig seeds were found. Finding grape seeds is a particularly important data because it demonstrates the earliest evidence of viticulture in Sardinia.
The only evidence of the Nuragic village dated to the Late Bronze Age and the First Iron Age (12th-8th century BC) are, so far, just storage pits, about 2 m deep, dug into the soil, some of them with their openings lined with sandstones slabs.
On the base of the study of faunal remains contained in the archaeological deposits, it has been assumed that the economy of Nuragic inhabitants in Sa Osa was characterized by activities of livestock breeding, hunting and fishing, the latter probably also practiced along the Tirso River.