The facts are briefly stated in Duval's Litterature syriaque, p. 192.
Probably (as Duval suggests) the use of Syriac in these regions went hand in hand with the spread of the monophysite doctrine, for the liturgies and formulas of the Jacobite Church were composed in Syriac. Similarly the spread of Nestorian doctrines throughout the western and southwestern regions of the Persian Empire was accompanied by the ecclesiastical use of a form of Syriac which differed very slightly indeed from that employed farther west by the Jacobites.
Bedjan, p. 115; cited by Duval, Litt.
The other, John bar Aphtonya, was the founder of the famous monastery of Kenneshre, opposite ' See Feldmann, Syrische Wechsellieder von Narses (Leipzig, 1896); Mingana, Narsai, homiliae et carmina (2 vols., Mosul, 1905); and other editions of which a list is given by Duval, p. 344 seq.
The Mrarrath gazze or Cave of Treasures, translated and edited by C. Bezold (Leipzig, 1883-1888), is akin (as Duval remarks) to the Book of Jubilees.