Journée d’étude du 28 octobre 2011, BnF, Salle des commissions.
From Ptolemy to Ahmad ibn Majid: Exploring the Transmission of Knowledge of the Western Indian Ocean
Marina Tolmacheva (Université de Washington)
The focus of the proposed study is the transmission of geographical knowledge of the Indian Ocean from the Red Sea to Madagascar. Locations along the East African coast recorded in Antiquity in the Periplus of the Erythraean Sea and the Geography of Ptolemy were among the data collected and translated by the early Arabic geographers. Ptolemy’s toponyms and their geographical coordinates from his tables of longitude and latitude were sometimes omitted, lost, or garbled in extant medieval manuscripts of the Islamic geographical works. However, his system of world geography made a lasting imprint on the methodology of geographical theoreticians and mathematical geographers from al-Khorezmi in the 9th century to al-Idrisi in the 12th century. The cartographic representation of theIndian Ocean in the Ptolemaic tradition in particular has been the focus of continuing puzzlement and fascination for historians of geography. The later cosmographers borrowed selected aspects of Ptolemaic methodology or at least paid lip service to his authority, without going back to the original source. Increasingly, there appeared to be a disconnect between the “academic” writing about and the practical knowledge of the Indian ocean by Arab and Muslim seafarers. The famed late-15th-century Omani pilot Ahmad ibn Majid and the 16th-century navigator Sulaiman al-Mahri left a significant written record of Arabic sailing instructions and maritime practice in the greaterIndian Ocean basin at the time of the Portuguese arrival. The paper addresses the information about the East African coast in the works of Ahmad ibn Majid from the perspective of ancient and medieval sources. The method is to trace across time the intersections of academic knowledge, of geographical information about, and practical navigation in the western and southwesternIndian Ocean. The goal is to observe, confirm or articulate the probabilities of knowledge transmission across time and different societies and civilizations.