Pre Celtic

The pre-Celtic languages of Europe and the southern littoral of the Mediterranean were either Indo-European or non-Indo-European. It is postulated that the non Indo-European language history can be seen as successive, but overlapping, layers:

Euro-African
Covering the western regions of the north African coast and stretching across southern and central Europe. Berber is assumed to be a relic of this layer. The eastern frontier of this group in Africa was presumably marked by the transition to the Egyptian of the Nile valley. Phoenician (Punic) is intrusive on the north African coast and south eastern Iberia.

Hispano-Caucasian
Covering the Iberian peninsula and Europe to the Caucasus. Aquitanian and its descendant, Basque is assumed to be a relic of this layer. The non Indo-European languages of south east Spain and south east France may also belong here.

Tyrhennian-Etruscan
Covering west central Italy and possibly Asia Minor. This layer is known to be intrusive in Italy where Etruscan is inserted between the Oscan and the Latin language regions.

There may be relics of other non Indo-European languages that are difficult to reconcile with this model. A good example is the proposed non Indo-European Pictish which, if accepted as a non Indo-European survival, would be isolated in Scotland.

That pre-Celtic Indo-European languages were spoken over a wider area than that occupied by the Celtic is evidenced by the existence of names (mainly hydronyms) that are clearly formed from Indo-European roots in areas that were never exposed to Celtic.

This then leads to the hypothesis that a broad uniform layer of Indo-European existed with pockets of non Indo-European preserved in north-western Spain and south-western France (proto Basque), the Mediterranean cost of Spain and and extending to south-western France (Iberian), south-western Iberia (Tartessan), Italy (Etruscan and north Picene), Switzerland and western Austria (Rhaetic) and possibly in the east Baltic region.