It has long been known that Christian Nubia used several dating methods, yet only one of them, the lunar calendar, drew scholars' more detailed attention. The present book is the first comprehensive analysis of all attestations of counting time in medieval Nubia known to date. It discusses nine different aspects of keeping track of time, divided into two parts: 'Annual dating methods' and 'Calendars'. The author on the one hand concentrates on indicating possible directions of influence that governed the use of particular dating methods in Nubia and on the other tries to prove the Nubians' own inventiveness in this field. Each chapter is supplied with a set of tables and maps faciliating the comprehension of the collected material. The book should be used together with an on-line resource for textual sources from Christian Nubia, 'The Database of Medieval Nubian Texts', to be launched in October/November 2011 at www.dbmnt.uw.edu.pl.