Did Basque ever have relatives, and can any of them still be identified?

Basque is the last pre-Indo-European language of western Europe and has no demonstrated relative. Proposals linking it to the Caucasian languages, to Iberian and to a wider Vasconic substrate have each been made and none has convinced. R. L. Trask, who assessed them, concluded that none of them meets the standard and that the honest answer is that we do not know, rather than that the relatives are contested. Aquitanian, the ancestor of Basque or its near relative, is attested only in Roman-era personal and divine names on inscriptions and reaches no further back.