It was the capital of the Giudicato of Cagliari, one of the kingdoms in which the island was divided in medieval times.
Parts of its remains are now found in Cagliari, as well as in the island of Sa Illetta.
The latter, in particular, built a port (Portus Scipio) on the shores of the Stagno di Santa Gilla.
In 718 Arab pirates launched their first raids against Cagliari, destroying sectors of the city and enslaving some inhabitants.
Starting from the 9th century AD, it became the seat of the giudice, the archbishop and the administration of the giudicato of Cagliari.