The Syriac historical tradition presents a valuable resource for Islamic history, a fact that is reflected by the growing number of historians who have drawn upon it in their studies of the early Islamic period. The Syriac tradition, however, is not immune to the long acknowledged historiographical complications in Arab-Islamic sources for this period. This reflects the state of Syriac source material in Islamic studies today: increasing popularity, but deficiency in source criticism. Several important Syriac chronicles only exist through later dependents and efforts to recover these lost chronicles have emerged as particularly important. My paper will introduce a methodology for reconstructing the lost Syriac chronicle of Dionysius of Telmaḥrē (d.845) based on both Arab-Islamic accounts and Dionysius’ dependents: Michael the Great (d.1199) and the anonymously authored Chronicle 1234. The chronicle of Dionysius is particularly valuable, beyond what it would contribute to the history of the ninth century, because it preserves the even earlier Syriac chronicle of Theophilus of Edessa (d.785). Robert Hoyland, in Theophilus of Edessa’s Chronicle, attempted to reconstruct the lost chronicle of Theophilus by translating the common material in Theophilus’ dependents: Dionysius (Syriac), Theophilus (Greek), and Agapius (Arabic). This impressive contribution, however, did not solve two major problems facing the Syriac tradition and Islamic history: how do we approach material that is not in both of Dionysius’ dependents? And when did the Islamic material enter the Syriac tradition? My project will address both of these problems by abandoning the search for a single source of all the Arab-Islamic material in the Syriac tradition along with the presupposition that a single Syriac author introduced all of the Arab-Islamic material. Rather, I will seek to demonstrate that Syriac historians introduced Arab-Islamic material at multiple times during a number of redactions. As a part of this process, the Syriac chroniclers incorporated Arab-Islamic material that reflected a uniquely Syriac sectarian perspective instead of haphazardly adopting the interpretation of their Arab-Islamic sources. This highlights the value for Syriac sources in two specific ways: first, even though later redactions of earlier chroniclers contain additions and or revisions, there is evidence that they preserve a distinct (and early) Syriac interpretation of Islamic history. Second, if Syriac chroniclers incorporated Arab-Islamic material that reflected their own interpretation, it suggests a context where the exchange of intellectual knowledge was dynamic and adaptable.