The Cauci (Καῦκοι) were a people of early Ireland, uniquely documented in Ptolemy's 2nd-century Geography, which locates them roughly in the region of modern County Dublin and County Wicklow.[1]
From the early 19th century, comparative linguists, notably Lorenz Diefenbach, identified the Cauci with the Germanic Chauci of the Low Countries and north-western Germany, a parallel already drawn by earlier antiquarian scholarship.[2] Proponents of this view also pointed to the fact that the Manapii (Μανάπιοι), who in Ptolemy's map border the Cauci to the south, likewise bear a name that is almost identical to that of another continental tribe, the Belgic Menapii in north-eastern Gaul.
This correspondence appeared to testify to population movements between the two regions. The linguistic aspect of this hypothesis was most recently (1917) developed by Julius Pokorny,[3] although the Cauci-Chauci association is not universally accepted.[4] This early scholarship also drew attention to apparent parallels among Celtic or Celticized peoples of the Iberian peninsula, specifically a leader of the Lusitani named Kaukainos (Καυκαῖνος), and a city called Kauka (Καύκα) (modern Coca), inhabited by Kaukaioi (Καυκαῖοι), among the Vaccaei, a prominent Celtic tribe of the Iberian Peninsula that spoke a Hispano-Celtic language.[5]
With regard to possible descendants of the Irish Cauci, Pokorny and Ó Briain[6] respectively favoured the obscure medieval septs of Uí Cuaich and Cuachraige, though in neither case has a connection been demonstrated.