The castle of Monreale was one of the main strongholds of the Giudicato of Arborea.

The four Sardinian Giudicati (fig. 1) of Cagliari, Arborea, Torres (or Logudoro) and Gallura were independent kingdoms, which were created between the VIII and IX century as a result of the isolation forced on the island because of the Arab expansion in the Mediterranean.

Fig. 1 - The Sardinian Giudicati from the eleventh to the fourteenth century (from http://upload.wikimedia.org/wikipedia/commons/c/c5/Giudicati_sardi_1.svg).

During the eighth century Sardinia was still part of the Byzantine Empire, but already by the end of the preceding century the imperial organisation had entered a crisis period and, at the same time, the first Arab threats began to appear against the coastal areas of the Mediterranean islands.

The exact processes which led to the gradual isolation of Sardinia are not known, but it is certain that the crisis of the Byzantine presence in the centre of the Mediterranean led to a power vacuum and exposed the island to the danger of Saracen raids.

During the Byzantine dominion, the island was governed by a praeses who took care of civil affairs, and by a dux, who led the exercitus Sardiniae.

In the eighth century, the office of praeses lost much of its authority and many of its functions were absorbed by that of the dux, until everything became concentrated into one person, the iudex Sardiniae.

It is likely that during the ninth century the iudex Sardiniae entrusted his lieutenants (lociservatores) to flank him with the political and military administration of the four most important territorial districts (partes) of the island.

Thereafter, each of them appointed himself judex and the Sardinian territory found itself divided into several autonomous units which took on the appearance of four independent kingdoms . The Giudicati resurface in known history after the year one thousand, already administratively and socially organised.

Each state was called Logu in Sardinian, and was headed by a monarch called judike.

One of the most important aspects of the organisation of the Giudicati is provided by the curatorie called partes: these were administrative districts consisting of a group of villages or "villas" (biddas) which depended on a “curatoria“ capital.

The curator was appointed by the King on a fixed-term basis, he managed the use of public lands, of the villas, organised the armed service and presided over the court. Each curatoria was self-sufficient and functional .

The Giudicato of Cagliari (fig. 2) was the largest (6000 sq. km) and the richest, its capital was Santa Igia (fig. 4). Its history ended in 1257.

The Giudicato of Arborea (fig. 2) had an area of 4500 square kilometres, its capital was first Tharros and then Oristano. This was the longest-running Giudicato as it fell, in fact, in 1410.

The Giudicato of Torres (or Logudoro, fig. 3) had as its capital Turris Libisonis first, then Sassari. Its history ended in 1259.

The Giudicato of Gallura (fig. 3) had as capital Civita (Olbia), and fell in 1298.

Fig. 2 - Coat of arms of the Giudicato of Arborea (on the left, from http://www.cavalierimacomer.com/macomer.html) and alleged coat of arms of the Giudicato of Cagliari (on the right, from http://it.wikipedia.org/wiki/Benedetta_di_Cagliari?uselang=it#mediaviewer/File:Cavallo_del_Giudicato_di_Cagliari.svg).

Fig. 3 - Coat of arms of the Giudicato of Torres (on the left, from http://it.wikipedia.org/wiki/Storia_della_Sardegna_giudicale#mediaviewer/File:Torre_Merlata_del_Giudicato_di_Torres.svg) and of Gallura (on the right, from http://commons.wikimedia.org/wiki/File:Gallo_del_Giudicato_di_Gallura.svg).

Fig. 4 - Ancient representation of Cagliari (from S. Igia capitale giudicale, Pisa 1986).