In 1164 Barisone, giudice of Arborea, was given the title of king of the whole island by Frederick Barbarossa, but his supremacy was never effective.
The island had (probably since the end of the 9th century) been divided into four districts - Cagliari, Arborea, Torres (or Logudoro) and Gallura - each under a giudice or remained a prisoner at Bologna until his death.
After this the Pisan supremacy of the island seems to have become more of a reality, but Arborea remained independent, and after the defeat of the Pisans by the Genoese at the naval battle of Meloria in 1284 they were obliged to surrender Sassari and Logudoro to Genoa.
The Aragonese enjoyed at first the assistance of the giudici of Arborea, who had remained in power; but in 1352 war broke out between Mariano IV.
After 1403 the Aragonese became masters of Arborea also.
In 687 Cagliari rose against the East Roman emperors, under Gialetus, one of the citizens, who made himself king of the whole island, his three brothers becoming governors of Torres (in the N.W.), Arborea (in the S.W.) and Gallura (in the N.E.
The Saracens devastated it in the 8th century, but were driven out, and the island returned to the rule of kings, until they fell in the 10th century, their place being taken by four "judges" of the four provinces, Cagliari, Torres, Arborea and Gallura.
The Pisans soon acquired the sovereignty over the whole island with the exception of Arborea, which continued to be independent.
It was not until 1403 that the kings of Aragon were able to conquer the district of Arborea, which, under the celebrated Eleonora (whose code of laws - the so-called Carta de Logu- was famous), offered a heroic resistance.
In the higher regions the principal trees are various species of fig, tamarind, carob and numerous kinds of cactiform Euphorbia, of which one, the Euphorbia arborea, grows to a height of 20 ft.
It was the seat from the 11th century onwards of the giudici (judges) of Arborea, one of the four divisions of the island.
Respectively to the S.S.E., were the scene of much fighting between the Aragonese government and the giudici and marquises of Arborea in the 14th and 15th centuries.