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. 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, although the Cauci-Chauci association is not universally accepted. 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.
With regard to possible descendants of the Irish Cauci, Pokorny and Ó Briain respectively favoured the obscure medieval septs of Uí Cuaich and Cuachraige, though in neither case has a connection been demonstrated.
- Ptol. Geog. 2.2.8 (ed. K. Müller [Paris 1883-1901]); P. Freeman, Ireland and the Classical World (Austin, Texas, 2001), pp. 69, 78-80
- L. Diefenbach, Celtica. Sprachliche Documente zur Geschichte der Kelten (Stuttgart 1839-40) I, pp. 414-15
- Julius Pokorny, "Spuren von Germanen im alten Irland vor der Wikingerzeit", Zeitschrift für celtische Philologie 11, 1917, 169-188 at 171
- T. F. O'Rahilly, Early Irish History and Mythology, Dublin Institute for Advanced Studies, 1946, pp. 24-25
- Appian, Iberica 51-2, 57; Zosimus, Historia Nova 4.24.4; L. Diefenbach, Celtica. Sprachliche Documente zur Geschichte der Kelten (Stuttgart 1839-40) I, pp. 320-21
- Micháel Ó Briain, "Studien zu irischen Völkernamen 1. Die Stammesnamen auf -rige", Zeitschrift für celtische Philologie 15, 1925, pp. 222-237