Proto-Euphratean language
Proto-Euphratean is a hypothetical unclassified language or languages which was considered by some Assyriologists (such as Samuel Noah Kramer) to be the substratum language of the people who introduced farming into Southern Iraq in the Early Ubaid period (5300–4700 BC). Igor Dyakonov and Vladislav Ardzinba identified these hypothetical languages with the Samarran culture.
Source: Wikipedia — Proto-Euphratean language (CC BY-SA 4.0)