In recent years there has been much interest in the non-Muslim sources that are roughly contemporary with early Arab rule and the emergence of Islam. An invaluable guide to the relevant sources, in a variety of different languages, was provided by R. Hoyland in his Seeing Islam as others saw it (1997). Among those sources in Syriac an important place is taken by the large corpus of letters by Isho‘yahb iii, the Catholicos Patriarch of the Church. Isho‘yahb iii was one of the most outstanding patriarchs in the history of the Church of the east, and many of that Church's liturgical texts are said to go back to reforms introduced by him. The edition of his letters runs to nearly 300 pages of Syriac text, but although it was published over a century ago, the fact that its accompanying translation is in Latin, and that the proposed English translation by P. Scott-Montcrieff never materialised, has meant that this important resource has not been exploited as much as it deserves. The present work is in fact the first full monograph to be devoted to Isho‘yahb iii. Ioan's study, which originated as a Göttingen dissertation, is set out in eight main chapters; the first four deal with his biography, covering his background, education and early years as a monk of the famous monastery of Beth ‘Abe (in north Iraq), followed by his ecclesiastical career as, successively, bishop, metropolitan and catholicos. The primary subject of the book is thus to be found in the last four chapters; these provide an outline of the Arab conquests in the areas that affected the Church of the east, a brief look at the consolidation of the Church in the years following the conquest, the various treaties that later sources retrospectively associate with Isho‘yahb ii, Mar'emeh and Isho‘yahb iii, and then an extended and valuable chapter specifically on Isho‘yahb iii and his specific references to Islam in the course of his correspondence. The paucity of these references (which explains the structure of the monograph) is to a considerable extent counterbalanced by their importance as a contemporary witness of someone for whom the new Arab rule was accepted as a given fact that need to be faced in a practical way as being part of divine providence, without showing any interest in the content or what the implications of emergent Islam might be for the Christian communities. The author's well-informed and critical approach makes this a very useful contribution.