History, Calendar and Skylore of the Incas at the Time of the Spanish Conquest

A significantly expanded translation of the author's Pachap vnancha: El calendario metropolitano del Estado Inca, this book is the culmination of several decades of research on Andean calendar-astronomical systems and their role in the ceremonial, economic and political aspects of the region's pre-Hispanic societies. This book presents a reconstruction of the state calendar used in Inca Tahuantinsuyu for purposes of programming, coordination and control of various social activities on an imperial scale. Although the correlation between Mesoamerican calendars and the Julian calendar has long been used to interpret events in that part of the world, this work is the first of its kind for the Andean region.

The work also discusses the techniques of astronomical observations during the Inca period and Andean specialists' predictions based on the interpretation of extraordinary phenomena, such as the appearance of comets or eclipses. The historical section presents the European and Inca calendar systems in parallel, focusing on the main events of the Conquest and the subsequent existence of the state of Vilcabamba until 1572. This new interpretative perspective clarifies the logic behind certain decisions made by the Incas, such as the seemingly “illogical” suspension of the siege of Cusco around May 12, 1536, when victory over the Spanish seemed certain. 

Online supplementary resources convert dates between Julian and Inca calendars for the period from 1500 to 1572.