International audience This article is devoted to the production and circulation of Syriac manuscripts, especially grammatical manuscripts, in the East and between East and West in the first part of the Ottoman period (fifteenth-fifteenth century), in relation to the various Syriac communities (Syrian Orthodox, Eastern Syriac Church, Maronites). Through the exchange of texts and copyists, it attempts at reconstructing the relations between these communities and the evolution of their linguistic and literary interests. Special attention is devoted to the reconstruction of the personal library of the Syrian Orthodox Patriarch Jean Bar Shayullah (15th cent.), its composition and its transfer to the West in the 16th century.