Basque remains an isolated language with no known linguistic relatives. The hypothesis of the German philologist Hugo Schuchardt (1842-1927), which once had wide currency, posited an intimate genetic connection between Basque and Iberian (see below) and the Hamito-Semitic (Afro-Asiatic) language group. This theory was superseded by attempts to establish a more or less close link between Basque and Caucasian, the language group indigenous to the Caucasus region. A lack of common linguistic characteristics between the Basque and Hamito-Semitic languages makes Schuchardt's hypothesis extremely dubious. There are, however, some common features that favour the relationship between Basque and Caucasian. Still, proof of a genetic relationship beyond reasonable doubt appears remote. Perhaps the most promising theory involves the comparison of Basque with the long-extinct Iberian, the language of the ancient inscriptions of eastern Spain and of the Mediterranean coast of France. But, despite amazing phonological coincidences, Basque has so far contributed next to nothing to the understanding of the now-readable Iberian texts. Therefore, it is possible that the similarity may have resulted from close contact between Basques and Iberians and not from a genetic linguistic relationship.