ERA. - It is a moment fixed in time, varying from people to people, corresponding to some great religious or national event, taken as the starting point for the reckoning of years.
I. ERA OF THE OLYMPIADS
Greek historians did not feel deeply the need for a uniform chronological criterion in their narratives: Thucydides himself counted the years both from the Trojan War and from the Battle of Marathon; moreover, every Greek state had its own calendar and its own era, which could hardly be made to correspond to those of the other states. Nevertheless, a term more or less common to all the Greeks was found in the reference to one of the four great national festivals: Olympian, Nemean, Isthmian and Pythian, and more precisely to the first, which prevailed over the others, being older by about two centuries.
After the Sicilian historian Timaeus (d. ca. 250 B.C.) made use of it in his Σιλεξινα, the era of the Olympiads was generally used by Greek writers, but among the various states there survived, in documentary usage, the system of counting the years from the series of eponymous magistrates: of the kings at Sparta, of the archons at Athens, and so on.
The Olympiad consisted of a period of four years, which were computed as I, II, III, IV of each Olympiad. It should be noted that the year of the Olympiad began with the full moon that preceded or followed the summer solstice: therefore, its beginning alternating between July and August, each year of an Olympiad corresponded to the second half of a Roman or Christian year, and to the first half of the following one.
Christian chronographers placed the birth of Jesus in the IV year of the 194th Olympiad, so that the I Olympiad would go back to 776 B.C.
The Olympian era was abolished by Theodosius the Great in 395 A.D. Nevertheless, until the 10th century, the word "Olympiad" is still found as a synonym of "four-year period" in the dating of some document (Olympiad IV of my reign: that is, "in the sixteenth year of my reign").
II. ERA OF ROME
In Rome, alongside consular dating (v. ANNO CONSOLARE), historians — though not documents — used to reckon the years from the founding of Rome. This date, however, while its day remained fixed (April 21), varies as to the year from author to author (for Cincius Alimentus 728 B.C., for Cicero 754, etc.). In the end the date of Varro prevailed, 753 B.C., as did that of Cato or of the Capitoline Fasti, 752 B.C.
The Varronian reckoning was the most used by historians and was also accepted by the moderns, for datings in solemn form of documents issued from the Capitol.
III. ERA OR PROVINCIAL YEAR, OF MAURETANIA
The numbering begins from A.D. 39. In inscriptions it is indicated by ann. prov. or ann. pr. or ann. p. Therefore, to obtain the modern reckoning, one must add 39 units.
IV. ERA OF SPAIN
Its starting point is A.D. 38; it was adopted not only in the Iberian Peninsula but also in the provinces occupied by the Visigoths in Gaul and in Africa. In Christian inscriptions it appears in the 3rd century in Cantabria, at the end of the 4th century in Merida, then in Lusitania, in Baetica, in Galicia in the second half of the 5th century; it becomes of general use under Visigothic rule; in the eastern zone never before the Mozarabic period. For the exact date one must subtract 38. (J. Vives, Inscripciones cristianas de la España Romana y Visigoda, I, Barcelona 1941, p. 7). In the inscriptions the words era, aera, in era, sub era are used, or the abbreviations er. or e. It disappears only in 1180 in Catalonia, in 1349 in Aragon, in 1358 in Valencia, in 1383 in Castile and León, in 1422 in Portugal.
V. ERA OF DIOCLETIAN OR OF THE MARTYRS
To the year 284, the date of the accession to the throne of the emperor Diocletian (the day oscillates between August and October), another era was traced back, which took its name from this emperor and was later called by Christians, beginning in the 7th century, the era of the martyrs, in memory of the great persecutions ordered by that emperor. Of Egyptian origin, it also spread through Europe; it was used by St. Cyril of Alexandria for his paschal tables, by Evagrius, by St. Bede; today it is in use among the Copts of Upper Egypt. In Milan it was also used by St. Ambrose, who dates epistle 23 (Episcopis per Aemiliam constitutis) "octogesimo et nono anno ex die imperii Diocletiani".
VI. BYZANTINE ERA
It is the most widespread of the computations that go back to the hypothetical date of the creation of the world, fixed by this era at 5508 B.C., so that the year 5509 corresponded to the first year of the Christian era. Introduced around the 7th century, it spread throughout the entire Orthodox East and was abolished in Russia only by Peter the Great on January 1, 1700. In Italy it was used in the southern regions also for the dating of documents, especially in the Greek language. For this era the year began on September 1.
VII. CHRISTIAN ERA
Introduced by the Scythian monk Dionysius Exiguus (d. 556), who spread in the West the table of Easter cycles compiled by Cyril of Alexandria, covering the years 437-531, and continued it from the following year: however, unlike Cyril, who calculated the years by the era of Diocletian, he wished to eliminate the name of the persecutor from his cycles, and considering that no historical event equaled in importance the coming of the Redeemer, he took this as the starting point for the reckoning of the years. He therefore fixed, albeit erroneously, the birth of Jesus Christ at 25 Dec. of the year 753 of Rome according to the Varronian reckoning, so that the year 754 ab urbe condita corresponded to the first of the new era. It was used at first only by chroniclers: it passed into public documents in England and France in the 8th century, in Germany in the 9th, in Spain in the 14th. In Italy the oldest examples are
from 890 and 961. At the end of the 9th century
it also appears in imperial documents,
where it becomes established in the following century; in
pontifical acts it appears with John XIII
in 968. Its use, however, was not uniform,
the date of the beginning of the year varying according
to the various styles (v. ANNO, inizio dell').
VIII. ERA OF THE PASSION
Used in
certain French charters up to the 11th century, it dates
years from an epoch that varies between
AD 31 and 34, taking as its point
of reference the crucifixion of Jesus Christ. In practice it was often confused with the Christian
era.
IX. MOHAMMEDAN ERA
It begins on July 1, 622, the date of Muhammad's flight to Medina (the Hegira), and follows the Islamic calendar based on lunar years, which are 10 or 11 days shorter than the solar year; consequently, 33 years of the Hegira correspond to 32 of ours.
The exact correspondence of a year of the Muhammadan era with that of the Christian era can therefore be found only by referring to chronological tables. The use of this era is found, besides in Arabic documents, also in Latin or vernacular versions of Arabic charters or texts.
BIBLIOTHE: in generale: R. Brinckmeier, Praktisches Handbuch
d. historischen Chronologie, Berlino 1882, pp. 10-62; F. Rühl,
Chronologie des Mittelalters und der Neuzeit, Berlino 1897, pp. 130-366; A. Giry, Manuel de diplomatie, nuova ed., Paris 1915,
pp. 88-93; A. Cappelli, Cronologia e calendario perpetuo, 2ª ed.,
Milano 1930; C. Paoli, Diplomatie, nuova ed. a cura di G. C.
Bascapè, Firenze [1942], pp. 103-214. Sulle è, del mondo
classico: [W.] Kubitschek, Aera, in Pauly-Wissows, I,
coll. 606-66; Bischoff, Kalender, ibid., X, II, coll. 1368-1602;
L. Ziehen, Olympia, ibid., XVIII, I, coll. 1-3; W. Kubitschek,
Grundriss der antiken Zeitrechnung (Handbuch der Klassischen
Altertumswissenschaft, I, 7), Monaco 1928. Sull'è. di Spagna:
I. Vives, Über Ursprung und Verbreitung der spanischen Aera, in
Histor. Jahrbuch, 58 (1938), pp. 97-108; id., Inscripciones cristianas de la España romana y visigoda, Barcellona 1942, pp. 177-190; A. Ferrua, Tombe che parlano, in Cro. Catt., 1943, IV,
pp. 97-99 e 166-71. Sull'è. maomettana: R. Campani, Calendario arabo, Modena 1914; [F.] Wüstenfeld-[E.] Mahler, Vergleichungs-Tabellen der mohammedianischen und christlichen Zeitrechnung, 2ª ed., Lipsio 1936.
Carmelo Trasselli-Alessandro Pratesi