Villamassargia is located in south-western Sardinia, within the historical region of Sulcis Iglesiente, more precisely, the village is located in the south-west of the Valle del Cixerri, which takes its name from the homonymous river.

Since the Neolithic period, the presence of man in this territory is attested. In this regard, of particular importance is the cave of Su Concali de Corongiu Acca, a natural cavity discovered in 1954 and frequented in the Early and Middle Neolithic, until the early Bronze Age. The cave, which has a length of 7.50 meters, had exclusive funerary function. It has returned ceramics ascribable to the culture of Bonu Ighinu, dating back to the first half of the fifth millennium BC, a tuff head depicting the mother goddess and a large number of human bones belonging to deceased of both sexes.

The Nuragic heritage is testified by the presence of numerous nuraghi, three giant tombs and some sacred wells, while there is no definite material evidence about the Phoenician-Punic period.
More numerous, however, are the archaeological evidence that attest to the attendance of the territory of Villamassargia in Roman times.
In fact, some remains of the ancient aqueduct that supplied the city of Calaris, today’s Cagliari, and that was also fed by the source of Capud'acquas, on the northern slopes of Mount Ollastu.

The Roman presence is also attested by the remains of ancient foundries, which reveal the importance of mining in this area, and a necropolis in Santa Barbara, whose tombs can be dated between the III and the I century B.C. Another tomb has been found in S'Arriali.

The scholars have found that the Roman Villamassargia was a reality of rural type, based mainly on the production of wheat, as it seems to indicate the name itself, which would derive from the Latin Villa Massaricia, but also on mining and pastoralism.

The importance of Villamassargia grew considerably in the Middle Ages. At that time the town was part of the territories of the Giudicato of Cagliari and became, before the birth of Villa di Chiesa, the capital of the Curatoria del Cixerri, establishing itself as one of the most populous centers of the Sulcis Iglesiente.

At that time Sardinia began to suffer the political and economic interference of Pisani and Genovesi, who had a decisive role in thwarting the attempt to conquer the island by the Arabs.

The Sardinian judges, grateful for the help, began to make concessions and donations to the two cities: this practice resulted in the concession to the Pisans of the castle of Cagliari in 1215, which sanctioned the political and military supremacy of the Tuscans over the entire Giudicato. The latter was definitively defeated by the Pisans in 1258: its territory was partly entrusted to the Donoratico della Gherardesca family of Pisa, who obtained control of all the Sulcis Iglesiente, dividing the various possessions.

The Curatoria of the Cixerri, to which Villamassargia also belonged, passed into the hands of Count Ugolino, while Gherardo was responsible for those of Sulci, Nora and Decimo. Later, following the death of Ugolino and the revolt of his son Guelph, subdued by the city of Pisa, also the Curatoria del Cixerri was incorporated into the domains of the family of Gherardo.
The main cultural sites of Villamassargia date back to the medieval period: the church of San Ranieri (later named after the Madonna del Pilar) and that of Santa Maria della Neve, the Castle of Gioiosa Guardia, S'Ortu Mannu and the historical residence "Casa Casula".

Villamassargia remained under Pisan rule until the arrival in Sardinia of the Catalan-Aragonese, who in 1324 conquered Villa di Chiesa.
The following year Villamassargia also fell into Aragonese hands.
From the historical and naturalistic point of view in Villamassargia there is a centuries-old olive grove in the town of S'Ortu Mannu and since 2008 it has been included in the list of Natural Monuments.
It is located at the foot of the hill on which the remains of the Castle of Gioiosa Guardia are still visible, about 4 km east of today’s town.
At the beginning the olive grove had an extension of about 500 hectares, now reduced to 12.

Of Phoenician-Punic plant, according to the most credited hypothesis during the period of Pisan domination the family of the Gherardesca counts, who became lords of the Curatories of Cixerri, Sulci, Nora and Decimo, promoted and encouraged the grafting of olive trees, The farmers would have to pay half of the product.
This practice was also maintained during the period of Catalan-Aragonese domination.
In 1436 an order of the viceroy of the Kingdom of Sardinia dates back, inviting the citizens of Villamassargia to graft the olive trees that were in the valley of Cixerri, in a place called "Bega de s'acqua" up to the town of "Santu Rumeu", for an extension of about 7 km.

It was common for tree owners not to be the same owners of the land where the shrubs were planted; this frequently caused conflict.
To overcome this problem, during the 90s of the twentieth century, the Municipality initiated an expropriation procedure, through which it acquired ownership of plants.
Private individuals have given the trees a symbolic figure of 1000 lire each to the municipal administration, in exchange for the right, also transmissible to heirs, of usufruct on the same tree for 99 years, with the commitment to look after pruning and care in general.
Currently in the garden there are about seven hundred specimens, each bearing a plate with the name of the usufructuary family that undertakes to care for and preserve it.
The number 556, for example, identifies Sa Reina (The Queen), a plant of about 900 years that, with its 16-metre-round trunk, is among the largest olive trees in the Mediterranean.