Language isolates in the context of "Sign languages"

The pre-Indo-European languages are any of several ancient languages, not necessarily related to one another, that existed in Prehistoric Europe, Asia Minor, Ancient Iran, and Southern Asia before the arrival of speakers of Indo-European languages. The oldest Indo-European language texts are Hittite and date from the 19th century BC in Kültepe (modern eastern Turkey), and while estimates vary widely, the spoken Indo-European languages are believed to have developed at the latest by the 3rd millennium BC (see Proto-Indo-European Urheimat hypotheses). Thus, the pre-Indo-European languages must have developed earlier than or, in some cases, alongside the Indo-European languages that ultimately displaced and replaced almost all of them.

A handful of the pre-Indo-European languages are still extant: in Europe, Basque retains a localised strength, with fewer than a million native speakers, whereas the Dravidian languages remain very widespread in the Indian subcontinent, with over 250 million native speakers (the four major languages being Telugu, Tamil, Kannada and Malayalam) and the Brahui that stretches into modern Iran. In the Caucasus, Northwest and Northeast Caucasian languages and Kartvelian languages are still intact, with the first having the least language security of the three pre-Indo-European Caucasian language groups. Some pre-Indo-European languages are attested only as linguistic substrates in Indo-European languages or in toponyms. In much of Western Asia (including Iran and Anatolia), the pre-Indo-European, Hurrian/Caucasian, Semitic languages, Dravidian and language isolates have survived to the present day, although Elamite has entirely disappeared.