early celtic-speakers left their traces in place names from ireland to anatolia, from scotland to the apennines, and from andalusia to the black sea. this original study reveals their full extent for the first time, exploiting a dataset of over 20,000 names recorded by greek and latin authors such as polybius, caesar and tacitus and by early geographers such as strabo, pliny, ptolemy and the ravenna cosmographer. patrick sims-williamss results are significant for archaeologists, historians and philologists studying the early distribution of celtic and other indo-european languages, while linguists will be interested in the novel methods he applies to linguistic geography.