I will examine the translation of medieval Arabic literature into Persian to explore the complimentary roles of Arabic and Persian in premodern Middle Eastern societies. After the emergence of written literary Persian after 900 CE, both Arabic and Persian served as lingua franca for religion and law, as well as for culture and trade. Both languages were included in one's education, because a text’s literary genre determined its language of composition, as is, for example, documented by the Arabic poetry by the renowned satirist ‘Ubayd-i Zakani (d. c.1370), and the Persian world history by the Shafi‘ite theologian Baydawi (d. 1316?). Most manuscripts of medieval translations of Arabic or Persian literature still await cataloguing and publication. Yet there is nonetheless sufficient codicological evidence to examine the origin and the reception of a few representative cases by analyzing the material evidence of their manuscripts and printed books, together with indirect evidence of their circulation in written sources, such as the «Kashf al-zunun» by Katip Celebi (1609-1657). My examples will juxtapose adab literature – the didactic animal fables of «Kalila wa-Dimna» of Ibn al-Muqaffa‘ (d. c.756) and the poetic anthology «Muhadarat al-udaba’» by Raghib (d. after 1050) – with reference literature – Raghib’s Quran dictionary «Mufradat fi gharib al-Qur’an» and the pharmacological treatise «Kitab al-abniya ‘an haqa’iq al-adwiya» by Abu Mansur al-Harawi (fl. 980-990). I argue that the nineteenth-century concept of a nation state with a single national language has made the complimentary uses of Arabic, Persian, and Ottoman in premodern Middle Eastern societies seem less relevant, as well as more difficult to conceptualize. Even medievalists tend to write the history of the book in the Middle East as the history of the Arabic book (e.g., J. Pedersen, Den arabiske bok, 1946; A. Gacek, Arabic Manuscripts, 2009), while giving short shrift to books written in Persian, Ottoman, and other languages. Consequently, specialists of Arabic and Persian manuscripts rarely compare notes (cf. articles by W. al-Qadi and I. Afshar in: Theoretical Approaches to the Transmission of Knowledge, eds. J. Pfeiffer and M. Kropp, 2007). My paper will explore whether the heuristic concepts of the 'Islamic book' - popular among art historians - and the 'manuscript in Arabic script' - preferred by paleologists – can lead to approaches that can successfully replace the reigning nationalist paradigms for research on the intellectual history of medieval Middle Eastern societies.