The Kitāb al-Masālik wa l-mamālik was written towards the end of the first half of the 10th century CE, by a certain Abū Isḥāq Ibrāhīm b. Muḥammad al-Iṣṭakhrī. The work built on the earlier concept of the “atlas of Islam”, which it developed further. The climates (iqlīm) it describes are no longer those of Ptolemean geography, but, reflecting the Iranian tradition, refer to geographical entities or “countries”. Also reflecting the author’s background—whose most common nisba is al-Fārisī—Iran holds a favoured position on this work. Published in 1870, the present edition by M.J. de Goeje was the first volume in the first series of the Bibliotheca Geographorum Arabicorum. In addition to the critical edition of the Kitāb al-Masālik wa l-mamālik, the online version contains the Praefatio, Addenda et emendanda, and the Indices and Glossarium that in the print version appeared in BGA volumes 1-2 and 1-4.