The Swiss linguist Johannes Hubschmid, one of the most renowned experts in substratum research, proposed six linguistic layers in prehistoric Sardinia. There is toponymic evidence suggesting that the Paleo-Sardinian language may have had connection to the reconstructed Proto-Basque and to the Pre-Indo-European Iberian language of Spain. Eduardo Blasco Ferrer concluded that it developed in the island in the Neolithic as a result of prehistoric migration from the Iberian peninsula. The author in his analysis of the Paleo-Sardinian language finds only a few traces of Indo-European influences, which were possibly introduced in the Late Chalcolithic through Liguria. Similarities between Paleo-Sardinian and Ancient Ligurian were also noted by Emidio De Felice. Bertoldi and Terracini propose that the common suffix -ara, stressed on the antepenult, was a plural marker, and they indicated a connection to Iberian or to the Paleo-Sicilian languages. Terracini claims a similar connection for the suffix -ànarV, -ànnarV, -énnarV, -ònnarV, as in the place name Bonnànnaro. A suffix -ini also seems to be characteristic, as in the place name Barùmini. A suffix or suffixes -arr-, -err-, -orr-, -urr- have been claimed to correspond to the North African Numidia, to the Basque-speaking Iberia and Gascony, and to southern Italy. The non-Latin suffixes -ài, -éi, -òi, -ùi survive in modern place names based on Latin roots. Terracini sees connections to Berber. Bertoldi sees an Anatolian connection in the endings -ài, -asài. A suffix -aiko is also common in Iberia and may have a Celtic origin. The tribal suffix -itani, -etani, as in the Sulcitani, has also been identified as Paleo-Sardinian.
Archeologist Giovanni Ugas suggested that the three main Nuragic populations may have had separate origins and so may have spoken different languages:
the Balares might have possibly been from the Iberian peninsula or Southern France and thus of either Proto-Iberian or Indo-European origin, linked to the Beaker culture.
The Corsi from the north-east might have possibly been of Ligurian origin.
The Iolaei/Ilienses, who inhabited the southern plains and today's Barbagia, might have probably spoken a Pre-Indo-European language similar to Minoan and other languages of that area.
The common subdivision of modern Sardinian into the three dialects of Gallurese, Logudorese and Campidanese might reflect that multilingual substratum. Other Paleo-Sardinian tribes of possible Indo-European stock were the Lucuidonensesfrom the north of the island, who might have been originally from Provence, where the toponymLugdunum is attested, and the Siculensi, perhaps related to the Siculi from Sicily, from the Sarrabus region.
