Present-day Basque is the modern form of the language spoken since prehistoric times in the Basque region (formerly larger than at present). Basque was already being used before the arrival of the Indo-European peoples.

It has not been possible to relate Basque with any degree of certainty to known linguistic groups, although attempts have been made to link it to Japanese, Amerindian languages, Uralian languages, Afro-Asiatic and Caucasian languages. Some scholars have attempted to categorise Basque, based on certain coincidences arising perhaps through linguistic contact with other languages or from vestiges of the Iberian civilisation, as the ancient pre-Roman language from the Mediterranean coastline of the Iberian Peninsula, but in-depth study of the language has dispelled the idea. Aquitaine names in Latin inscriptions in the south-west of Gaul, and which can be clearly related with Basque forms, suggest a close link between Aquitaine, the pre-Roman language of present-day Gascony, and Basque.

Aquitaine would be the predecessor of Basque or perhaps both belonged to a single family of languages which extended throughout the region of the Bay of Biscay. There are six dialect subgroups in Basque (Biscayn, Guipuzcoan, High Navarrese, Labourdin, Low Navarrese and Souletin). Dialectical differences do not hinder comprehension between speakers of the different variants. In the 1960s the modern standard language was established based on Guipuzcoan and, to a lesser extent, on the Labourdin orthography.