Sinyar (tààr ꜝʃàmɲà {mouth=language/Sinyar}) is an underdocumented language spoken by some 20.000 speakers living in Western Darfur and extending on the Chadian side of the border with Sudan (see Map). Up to now Sinyar has been considered a member of the SBB (Sara-Bongo-Bagirmi) branch of Central Sudanic languages (Tucker & Bryan 1956; Haaland 1978; Doornbos & Bender 1983, Bender 1992). However Doornbos ([1980?]: 1) himself questioned this classification as he wrote the first grammatical sketch of the language some forty years ago (see epigraph above). Further research recently devoted to Sinyar confirms Doornbos’ view: although Sinyar shares many lexical and morphosyntactic features with the neighbouring SBB languages, it also differs of them on many other points so that it looks, to some extent, as a ‘mixed’ language, the ‘non-SBB’ component of which, however, has not been identified until now.1 The aim of this paper is to review different Sinyar features that are respectively similar to and distinct from features characteristic of the SBB languages. By doing so I want to – define the two sources of Sinyar and clarify its nature of ‘mixed’ language; – try to identify the SBB languages Sinyar is the closest to; – tentatively answer the tricky question of its genesis, i.e. was Sinyar originally an SBB language that underwent a strong foreign influence or, rather, was Sinyar an exogenous language that integrated numerous features of certain SBB languages he got a significant contact with? In other words are there clues suggesting that the ‘non-SBB’ part of Sinyar represents an adstrate or a substrate?