One of the pleasures of cataloging manuscripts is learning about authors and texts that are relatively little known. One such Syriac author is Athanasios (Abū Ġalib) of Ǧayḥān (Ceyhan). Two fifteenth-century manuscripts, CFMM 417 and 418, which I have recently cataloged, each contain different texts attributed to him. Barsoum surveys his life and work briefly in Scattered Pearls (pp. 441-442), and prior to that Vosté wrote an article on him; more recently Vööbus and Carmen Fotescu Tauwinkl have further reported on him. (See the bibliography below; I have not seen all of these resources.) According to Barsoum, he died in 1177 at over 80 years old. As far as I know, none of his work has been published.
The place name associated with this author is the Turkish Ceyhan. The Syriac spelling of the place in the Gazetteer has gyḥʾn, but in both of these manuscripts it is gyḥn. The former is probably an imitation of the Arabic-script spelling, while the form without ālap in the manuscripts still indicates ā in the second syllable by means of an assumed zqāpā.
Now for the CFMM texts.
CFMM 417, pp. 465-466
An untitled monastic selection. These two pages make up the whole of this short text. As you can see, it follows something from Isaac of Nineveh, and it precedes Ps.-Evagrius, On the Perfect and the Just (CPG 2465 = Hom. 14 of the Liber Graduum). The manuscript is dated March, 1785 AG (= 1474 CE).
CFMM 418, ff. 235v-243v
Excerpts “from his teaching”. Here are the first and last pages of the text. This longer text follows Isaac of Nineveh’s Letter on how Satan Takes Pains to Remove the Diligent from Silence (ff. 223v-235v, Eggartā ʿal hāy d-aykannā metparras Sāṭānā la-mbaṭṭālu la-ḥpiṭē men šelyā) and precedes some Profitable Sayings attributed to Isaac. This manuscript — written by more than one scribe, but at about the same time, it seems — is dated on f. 277v with the year 1482, but the 14- is to be read 17-, so we have 1782 AG (= 1470/1 CE; cf. Vööbus, Handschriftliche Überlieferung der Mēmrē-Dichtung des Jaʿqōb von Serūg, III 97).
Tauwinkl, Carmen Fotescu, “Abū Ghālib, an Unknown West Syrian Spiritual Author of the XIIth Century”, Parole de l’Orient 36 (2010): 277-284.
Tauwinkl, Carmen Fotescu, “A Spiritual Author in 12th Century Upper Mesopotamia: Abū Ghālib and his Treatise on Monastic Life”, Pages 75-93 in The Syriac Renaissance. Edited by Teule, Herman G.B. and Tauwinkl, Carmen Fotescu and ter Haar Romeny, Robert Bas and van Ginkel, Jan. Eastern Christian Studies 9. Leuven / Paris / Walpole, MA: Peeters, 2010.
Vööbus, Arthur, History of Asceticism in the Syrian Orient: A Contribution to the History of Culture in the Near East, III, CSCO 500, Subs. 81. Louvain: Secrétariat du CorpusSCO, 1988, pp. 407-410.
Vööbus, Arthur, “Important Discoveries for the History of Syrian Mysticism: New Manuscript Sources for Athanasius Abû Ghalîb”, Journal of Near Eastern Studies 35:4 (1976): 269-270.
Vosté, Jacques Marie, “Athanasios Aboughaleb, évêque de Gihân en Cilicie, écrivain ascétique du XIIe siècle”, Revue de l’Orient chrétien III, 6  (1927-1928): 432-438. Available here.