 The conquest of Sicily by these groups in 827 effectively cut Sardinia off from the central government and military might of the Byzantine Empire.In the absence of instruction or reinforcement, the Sardinian provincial Byzantine officials, called "iudici" ("judges") began to govern autonomously.By the tenth century the island was divided into four of these provinces ("giudicati", literally, "judgeships"), though two — Logudoro and Arborea — were combined at the start of the eleventh century.