Siwi is the easternmost Berber language, one of the few surviving representatives of the languages spoken in the eastern Sahara before the arrival of Bedouin Arab groups in the 11th century – although this apparent continuity conceals a history of migration, as this book argues based on loanwords and intra-Berber relationships.  The effects of contact upon the grammar are far more far-reaching than in better documented westerly Berber languages, extending to non-concatenative templatic morphology and some pronominal endings, as well as prominent calquing.  Siwi itself is inadequately documented and under threat; this book, based on in situ fieldwork, describes Siwi grammar in greater detail than any previous publication, reporting many hitherto unattested constructions.  The appendix includes a selection of Siwi texts spanning multiple genres – public speech, description, storytelling, poetry – and produced by speakers of different ages.