The church, dating from the Greek-Byzantine period, has an inscribed Greek cross shape, making it the only one of its kind in all of Sardinia. Inside are preserved inscriptions in ancient Greek, only a few words of which remain today because following restoration work in 1919 the rest were lost. From the few remaining words it is possible to date the church to the 8th century.
The earliest historical documentation of Assemini and the church of St. John dates back to the early 12th century when Sardinia was in the hands of the Papal States. On June 18, 1107, an agreement was made between Genoa and the Cagliari judge, Tokitorio II, in favor of the chapter of the Genoese church of St. Lawrence, which was the beneficiary of the agreement. The donikalia of
Arsemine and all its inhabitants is ceded by the judge from Cagliari; in the document of the agreement the names of the heads of the families are listed, so that none of them can escape the change of master, in which the formula is added the Latin text that says ” with wife and all sons and daughters.” This is an outstanding document that allows us to know the names of this ancient community. In 1108 the “Judike Mariane,” bearing the title of Torkitorio II, must also cede the church of St. John’s to the Major Church of St. Lawrence of Genoa.
