Bahra Hassab: Yezemen Qotera Qirsachen;

Bahra Hassab, the title of the book means “computus”. It discusses the mathematical system which the Ethiopian and Coptic Orthodox Churches use for fixing their movable feasts and fasts. A perpetual calendar for the said feasts and fasts is also given in a table of 532-year cycle. The other content of the book related to the computus is a table that synchronizes the Ethiopian (Julian) calendar with the western (Gregorian) calendar for the years AD 1261 to AD 2316. In addition, the book records chronologically the history of Ethiopia from AD 1 to the present, AD 2000.