This project aims to investigate the way in which astrological knowledge practices are used in scientific, historiographical and eschatological texts in the late fourteenth and early fifteenth century Syro-Egyptian Mamlūk Sultanate (ca. 1250-1517). More specifically this project will focus on the use these texts make of the hitherto neglected practices of calculating planetary conjunctions. This will be studied on three levels. On a disciplinary level the project will study how categories within the science of the stars are delineated and which place calculations of planetary conjunctions occupy within these categories. On the level of the textual genres, the use to which calculations of planetary conjunctions are put in the different text genres will be studied. In manuals for timekeeping the project will investigate how calculations of planetary conjunctions are linked to certain events. In chronicles and eschatological texts attention will be paid in particular to the extent to which the writers of these texts appropriate the calculations in creating an image of the past or the future which suits or rationalises their own position in society. On a third level, specific textual references to Abu Ma'shar’s (d. 887) influential conjunctionalist theory will be taken into account, as this theory circulated in the sultanate in this period.