My presentation will look into a vexed problem: when and how did Arabic historical and ḥadīth writing become separate fields of scholarship (or did they ever)? That is, who was responsible for the idea that ḥadīths, “Prophetic traditions” and khabars, “historical reports” were different? These two intertwined genres of Arabic literature (historiography and Prophetic dicta) developed during the second/eighth centuries. Of major importance were such early authorities as ʿUrwa ibn al-Zubayr (d. 94/712), al-Zuhrī (d. 124/742), and Ibn Isḥāq (d. ca. 150/767), who form, in fact, a neat chain of teacher-student relationships. None of their works are extant but their material survives in quotations in later Arabic works. The possibilities – and problems – of reconstructing their works has been explored by Nicolet Boekhoff-van der Voort, Andreas Görke, Harald Motzki, and Gregor Schoeler, so we have rather clear idea what these works might have included. It must be noted, however, that none of them wrote books with fixed forms but rather transmitted their material in lecture-based environment. Of significance are also those early authorities whose enmity Ibn Isḥāq aroused, namely, Mālik ibn Anas (d. 179/795) and Hishām ibn ʿUrwa (d. 146/763). By probing the interdependence and tension between the writers of the historiography and Prophetic traditions genres (if we can call them separate genres), I hope to explain the nature of the relationship among these genres and their historical provenance. An angle that I will provide and that has been often ignored is to look at a form of Arabic historical writing that was independent of Islamic sacred history: the Siyar al-mulūk works. They were translations (or adaptations) into Arabic of the Middle Persian Khwadāy-nāmags, “Books of Kings.” The Arabic versions were composed by such authors as Ibn al-Muqaffaʿ (d. ca. 139/757) and al-Kisrāwī (d. third/ninth c.?). The Siyar al-mulūk genre flourished in the second–third centuries AH but their contribution to Arabic historiography has usually been forgotten. The works (mostly lost) were more or less isnād-less, continuous narration in which mythical Persian history was synchronized with Biblical history. It will be claimed that the Siyar al-mulūk works affected Ibn Isḥāq and later authors profoundly in their search for the form of Islamic historiography. The role of the early ʿAbbāsid dynasty, which first supported Ibn al-Muqaffaʿ but afterwards had him killed, and started supporting Ibn Isḥāq’s scholarly efforts instead, will also be underlined in my presentation.