Arabic, Berber and in an unspecified "town language", which might be interpreted as a Romance variety; in the oath, the Arabic-rendered phrase bar diyyu could represent some variation of Latin per Deu(m) ("by God".) In their quest to conquer the Kingdom of Africa in the 12th century, the Normans were aided by the remaining Christian population of Tunisia, who some linguists, among them , argue had been speaking a Romance language for centuries. The final attestations of African Romance come from the Renaissance period. The 15th century Italian humanist makes the most significant remarks on the language and its features, reporting that a Catalan merchant named Riaria who had lived in North Africa for thirty years told him that the villagers in the Aurès mountain region "speak an almost intact Latin and, when Latin words are corrupted, then they pass to the sound and habits of the Sardinian language". The 16th century geographer and diplomat Leo Africanus, who was born into a Muslim family in Granada and fled the Reconquista to Morocco, also says that the North Africans retained their own language after the Islamic conquest which he calls "Italian", which must refer to Romance. A statement by Mawlâ Aḥmad is sometimes interpreted as implying the survival of a Christian community in Tozeur into the eighteenth century, but this is unlikely; Prevost estimates that Christianity disappeared around the middle of the thirteenth century in southern Tunisia. Related languages The Sardinian hypothesis The most prominent theory for the classification of African Romance (at least for the interior province of Africa Proconsularis) is that it belonged to a shared subgroup along with Sardinian, called Southern Romance by some linguists. This branch of Romance, of which Sardinian would today be the only surviving member, could have also been spoken in the medieval period in Corsica prior to the island's Tuscanization, southern Basilicata (eastern region of the Lausberg area) and perhaps other regions in southern Italy, Sicily and possibly even Malta. A potential linguistic relationship between Sardinia and North Africa could have been built up as a result of the two regions' long pre-Roman cultural ties starting from the 8th-7th centuries BC, when the island fell under the Carthaginian sphere of influence. This resulted in the Punic language being spoken in Sardinia up to the 3rd–4th centuries AD, and several Punic loan-words survive into modern Sardinian. Cicero also mocks Sardinia's perceived Carthaginian and African