section_path: Ancient dating systems/Indiction cycles
section_name: Indiction cycles
paragraph_text: Indiction cycles
  
  The indiction cycle was an agricultural tax cycle implemented in Roman Egypt. 15 indictions made up the cycle, an indiction being a year in duration. Documents and events began to be dated by the year of the cycle (e.g., "fifth indiction", "tenth indiction") in the 4th century, and this system was used long after the tax ceased to be collected. It was used in Gaul, in Egypt until the Islamic conquest, and in the Eastern Roman Empire until its conquest in 1453.
  
  A useful chart providing all the equivalents can be found in Chaîne's book on chronology, and can easily be consulted online at the Internet Archive, from page 134 to page 172.
  
  A rule for computing the indiction from an AD year number was stated by Dionysius Exiguus: add 3 and divide by 15; the remainder is the indiction, with 0 understood to be the fifteenth indiction.: 770 Thus the indiction of 2001 was 9. The beginning of the year for the indiction varied.: 769–71