List of ancient Celtic peoples and tribes

The ethnic names of this List of ancient Celtic peoples and tribes are stated or implied by the ancient authors to have belonged to an overall ethnic identity called by them generally Celts. Some of the main authors, such as Julius Caesar, explicitly state that Celtic, the adjective, implies the use of a distinctive Celtic language. If a tribe did not speak Celtic, it was not called Celtic. This implication is sufficiently widespread for modern linguists to conclude that if a tribe was called Celtic, it spoke Celtic.

From widespread evidence in literature, inscriptions, and names, modern linguists are able to conclude to a group of closely related languages termed Celtic languages. Linguistic classification of languages by the Tree Method, or Genetic Method, which establishes degree of similarity of vocabulary and syntax between languages, can be used to assign a relationship of one language to another. Closely similar languages are closely related by definition. This relationship is termed ethnolinguistic.

An ethnolinguistic relationship has nothing to do with biological genetic relationships. Two populations may be close ethnolinguistically but totally different genetically, as when one population learns the language of another. Similarly the customs of two populations apart from language have nothing to do with either the people or the language. Among such customs are the archaeologies. The archaeological finds and culture names have nothing to do with the langage, except for inscriptions found. This article attempts to arrange Celtic languages by ethnolinguistic similarity. Nothing is impled concerning the origins of the peoples or their material culture.

In Classical antiquity, Celts were in large number and were a significant part of the population in many regions of Western Europe, Southern Central Europe, the British Isles, parts of the Balkans, and also Central Asia Minor or Anatolia.

Modern people and their languages are excluded from this list. A few Celtic languages are still extant. They are not of interest here.