In the Sulcis there are words for how a village comes into being, and Masainas went through all of them: first it was a medau, that is an isolated farmstead, then a boddeu, that is a cluster of farmsteads, and it grew around its little church towards the end of the seventeen hundreds; out in the country the furriadroxius remain, the old scattered farmhouses. But the territory had been inhabited long before. In the Is Solinas area there are Neolithic settlements, then came the nuraghi — more than ten are counted, among them the complex of Is Fais, which has four towers set in a cross — then the Phoenician-Punic infiltrations and, between the third and the second century before Christ, the Romans, who reached the interior after the conquest of Solki, today's Sant'Antioco. From that period some curious things remain: between Masainas and Giba the remains of what looks like a factory of terracotta tools, and above all stone sarcophagi of the Roman age turned up by chance, whose peculiarity is that those burials were made in sandy ground, and are for that reason unique in Sardinia.
Around the twelve hundreds Benedictine monks came here to preach and built convents, the guventus, and to those the name of one district of the comune still refers, Su Guventu. The only monument of note is the church of San Giovanni Battista, and about its age there is no agreement: the Gothic-Aragonese influence would place it in the fifteen or sixteen hundreds, but some scholars speak of the year one thousand or a little later, in which case it would be late Romanesque. In 1839 Masainas was the largest settlement of the area, with four hundred and forty-seven families and one thousand eight hundred and six inhabitants — that is, more people than it has today — and it followed the fortunes of the marquisate of Palmas. From the heights the territory slopes gently down to the sea at Porto Botte, with a shore of white sand dunes and thick juniper: in 1989 the Region included part of it in the plan of natural parks. Since 2003, every April, the artichoke festival is held.