This volume is the first critical edition of a medieval almanac from the Arabian Peninsula. It presents the Arabic text, an English translation, and a detailed analysis of a thirteenth-century agricultural almanac (dated by internal evidence to A.H. 670-71/A.D. 1271) compiled by the Yemeni sultan al-Malik al-Ashraf Umar ibn Yusuf, the third sultan of the Rasulid dynasty (13th-15th cent.).

This almanac comprises one chapter of al-Ashraf's scientific treatise Kitab al-Tabsira fi ilm al-nujum (Instruction in the science of astronomy and astrology). Al-Ashraf's is the earliest and most detailed of eight extant Rasulid almanacs.

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The almanac as a literary and scientific genre in Arab tradition has received little scholarly attention, although hundreds of manuscripts exist. This study of almanac information draws the reader across the arbitrary boundaries of disciplines into the full array of medieval science and esoterica.

Al-Ashraf's almanac contains information on astronomy, astrology, time-keeping, meteorology, plants and animals, agriculture (including tax periods), health, and navigation not only for Yemen but for other parts of the medieval world as well. It is the earliest source to document the dates of the Indian Ocean sailing periods to and from the port of Aden. The almanac provides a view of a medieval trading network extending from North Africa and southern Europe to the Indian Ocean and China.

Information in the almanac is derived from both the general Islamic almanac tradition and ethnographic knowledge of local practice and folklore. Although the almanac is not meant to be a descriptive record of the agricultural cycle, for example, it is obvious that most of the information is based on observation of actual practices and on knowledge of folklore.

Details of the Yemeni agricultural cycle, primarily for the coastal region and the southern highlands, are extremely valuable and supplement discussions in extant Rasulid agricultural and tax treatises.

Varisco's extensive commentary explains how the terminology and concepts of al-Ashraf's text are related to those of earlier and contemporaneous scientific texts throughout the Islamic world and uses his own ethnographic research on Yemeni rural economy and folklore to enhance his interpretation of the almanac. One of the rewarding aspects of studying the Yemeni almanacs is that many of the agricultural activities mentioned can still be observed and documented.

The study of a medieval almanac as part of a living tradition can be accomplished in Yemen better perhaps than anywhere else in the Arab world. The older generation still retains much of the accumulated agricultural and environmental lore from scores of previous generations.

Not only would it be impossible to understand some of the almanac terminology without knowledge of present-day Yemeni dialects, but ethnographic study of traditional agriculture and folk science, despite changes over time, helps in the interpretation of old written sources.

Because al-Ashraf's almanac addresses a wide range of subjects, readers from diverse disciplines will find this volume of value. Not only will it be a basic reference for anyone interested in Yemen, both ancient and modern, but it has much to offer scholars of medieval economy, science, and technology. Varisco's textual approach of combining historical and contextual analysis with ethnographic fieldwork further enhances the appeal and value of this study.