on the Gregorian Dates of '12 September 1999' and '2003' respectively. This date correspondence applies for the Gregorian years 1900 to 2099. The Ethiopian calendar leap year is every four without exception, while Gregorian centurial years are only leap years when exactly divisible by 400; thus a set of corresponding dates will most often apply for a single century. As the Gregorian year 2000 is a leap year, the current correspondence lasts two centuries instead. The start of the Ethiopian calendar year (Feast of El-Nayrouz) falls on 29 or 30 August (in the year just before the Julian leap year). This date corresponds to the Old-Style Julian Calendar; therefore, the start of the year has been transferred forward in the currently used Gregorian Calendar to 11 or 12 September (in the year just before the Gregorian leap year). This deviation between the Julian and the Gregorian Calendar will increase with the passing of the time. Eras To indicate the year, followers of the Ethiopian and Eritrean churches today use the Incarnation Era, which dates from the Annunciation or Incarnation of Jesus on 25 March AD 9 (Julian), as calculated by Annianus of Alexandria c. 400; thus its first civil year began seven months earlier on 29 August AD 8. Meanwhile, Europeans eventually adopted the calculations made by Dionysius Exiguus in AD 525 instead, which placed the Annunciation eight years earlier than had Annianus. This causes the Ethiopian year number to be eight years less than the Gregorian year number from January 1 until 10 or 11 September, then seven years less for the remainder of the Gregorian year. In the past, a number of other eras for numbering years were also widely used in Ethiopia, Eritrea, and the Kingdom of Aksum. Calendars of the world The most important era – once widely used by Eastern Christianity, and still used by the Coptic Orthodox Church of Egypt was the Era of Martyrs, also known as the Diocletian Era, or the era of Diocletian and the Martyrs, whose first year began on 29 October 328. Respective to the Gregorian and Julian New Year's Days, 3 to 4 months later, the difference between the Era of Martyrs and the Anno Domini is 285 years (285= 15×19). This is because in AD 525, Dionysius Exiguus decided to add 15 Metonic cycles to the existing 13 Metonic cycles of the Diocletian Era (15×19 + 13×19