In 1073, the veil of obscurity that had long shrouded Sardinia's history after its independence from the Eastern Roman Empire was finally lifted. This pivotal moment revealed an island strictly organised from an administrative perspective. The Sardinians were now divided into four kingdoms, each governed by a judge—a distinct figure within the medieval European institutional landscape: the Judicate of Arborea, the Judicate of Torres, the Judicate of Gallura, and the Judicate of Càlari.

From 534—the year of the end of the Vandalic War, fought between the Byzantines and the Vandals—Sardinia was part of the possessions of the Eastern Roman Emperor, adopting the Hellenic-Byzantine cultural characteristics and the characteristic form of government presided over by a dux with military functions and a praeses with civil duties. With the arrival of the Arabs and the looming threat they posed to the western Mediterranean, our sources on the island's fate and its form of government grew increasingly obscure. The only figure we glimpse before the emergence of the Giudicati is that of the Archon, a high-ranking Byzantine official who unified military and civil functions, likely to expedite responses to the increasingly frequent Arab incursions along the island's coasts.

The four-way division of medieval Sardinia into Giudicati is only clearly shown in sources from 1073. We know for certain they existed from this date, as evidenced by a letter sent by Gregory VII to the four Giudicati: Orzocco d'Arborea, Orzocco di Càlari, Mariano di Torres, and Costantino di Gallura. In this letter, the Pope disapproves of how slowly Christianity is spreading in the interior, where, he claims, people still worship false gods. He also criticises the fact that local beliefs remain close to Eastern ones, as shown even now by the veneration of Saint Constantine, a saint in the Orthodox but not the Catholic Church, in many parts of Sardinia.

The letter from Gregory VII does not explain how Sardinia went from being ruled by an archon to being divided into four Giudicati. Experts rely on guesses. The most common idea is that, as Sardinia became increasingly independent of Constantinople due to Arab gains in North Africa, leaders created a new office free of the emperor’s control. This office lost power to local families, who then became the rulers of the Giudicati.