The 4th century was the time period which lasted from 301 to 400. In the West, the early part of the century was shaped by Constantine the Great, who became the first Roman emperor to adopt Christianity. Gaining sole reign of the empire, he is noted for re-establishing a single imperial capital, choosing the site of ancient Byzantium in 330 to build the city soon called Nova Roma; the last emperor to control both the eastern and western halves of the empire was Theodosius I. As the century progressed after his death it became apparent that the empire had changed in many ways since the time of Augustus; the two emperor system established by Diocletian in the previous century fell into regular practice, the east continued to grow in importance as a centre of trade and imperial power, while Rome itself diminished in importance due to its location far from potential trouble spots, like Central Europe and the East. Late in the century Christianity became the official state religion, the empire's old pagan culture began to disappear.
General prosperity was felt throughout this period, but recurring invasions by Germanic tribes plagued the empire from AD 376 onward. These early invasions marked the beginning of the end for the Western Roman Empire. In China, the Jin dynasty, which had united the nation prior in 280, began to face troubles by the start of the century due to political infighting, which led to the opportunistic insurrections of the northern barbarian tribes, which overwhelmed the empire, forcing the Jin court to retreat and entrench itself in the south past the Yangtze river, starting what is known as the Eastern Jin dynasty around 317. Towards the end of the century, Emperor of the Former Qin, Fu Jiān, united the north under his banner, planned to conquer the Jin dynasty in the south, so as to reunite the land, but was decisively defeated at the Battle of Fei River in 383, causing massive unrest and civil war in his empire, thereby leading to the fall of the Former Qin, the continued existence of the Eastern Jin dynasty.
According to archaeologists, sufficient archaeological correlates of state-level societies coalesced in the 4th century to show the existence in Korea of the Three Kingdoms of Baekje and Silla. Historians of the Roman Empire may refer to the "Long Fourth Century", the period spanning the fourth century proper, but starting earlier with the accession of the emperor Diocletian in 284 and ending with the death of Honorius in 423 or of Theodosius II in 450. Noba people settle in Africa. Early 4th century – Former audience hall now known as the Basilica, Germany, is built. 301: Armenia first to adopt Christianity as state religion. 306 – 337: Constantine the Great, ends persecution of Christians in the Roman Empire and Constantinople becomes new seat of government. 325 – 328: The Kingdom of Aksum adopts Christianity. 325: Constantine the Great calls the First Council of Nicaea to pacify Christianity in the grip of the Arian controversy. 335 – 380: Samudragupta expands the Gupta Empire. 337: Constantine the Great is baptized on his death bed.
350: About this time the Kingdom of Aksum conquers the Kingdom of Kush. 350 – 400: At some time during this period, the Huns began to attack the Sassanid Empire. 350: The Kutai Martadipura phase in East Kalimantan produced the earliest known stone inscriptions in Indonesia. 365: an earthquake with a magnitude of at least eight strikes the Eastern Mediterranean. The following tsunami causes widespread destruction in Crete, Libya, Egypt and Sicily. Mid-4th century – Dish, from Mildenhall, England, is made, it is now kept at London. Mid-4th century – Wang Xizhi makes a portion of a letter from the Feng Ju album. Six Dynasties period, it is now kept at National Palace Museum, Taiwan, Republic of China. 376: Visigoths appear on the Danube and are allowed entry into the Roman Empire in their flight from the Huns. 378: Battle of Adrianople: Roman army is defeated by the Visigoth cavalry. Emperor Valens is killed. 378 – 395: Theodosius I, Roman emperor, bans pagan worship, Christianity is made the official religion of the Empire.
378: Siyaj K'ak' conquers Waka on January 8. 378: Siyaj K'ak' conquers Tikal on January 16. 378: Siyaj K'ak' conquers Uaxactun. 381: First Council of Constantinople reaffirms the Christian doctrine of the Trinity by adding to the creed of Nicaea. 383: Battle of Fei River in China. 395: The Battle of Canhe Slope occurs. 395: Roman Emperor Theodosius I dies, causing the Roman Empire to split permanently. Late 4th century – See "The Historia" of Arbogast and Bauto. Late 4th century – Cubiculum of Leonis, Catacomb of Commodilla, near Rome, is made. Late 4th century – Atrium added in Old St. Peter's Basilica, Rome. Aelia Eudoxia, Roman Empress. Alaric I, King of the Visigoths Albia Dominica, Roman Empress and regent. Arbogast, Roman general and rebel. Arcadius, Roman Emperor. Atlatl Cauac, ruler of Teotihuacan Bassianus, Roman candidate for the position of Caesar. Calocaerus, Roman usurper. Chak Tok Ich'aak I reign 14th dynastic ruler of Tikal Chandragupta I, Gupta emperor Chandragupta II, Gupta emperor Claudius Silvanus, Roman general and usurper.
Constans, Roman Emperor. Constantina, Roman Augusta (between 307 and
The Republic of China calendar is the official calendar of the Republic of China. It is used to number the years for official purposes only in the Taiwan area after 1949, it was used in the Chinese mainland from 1912 until the establishment of the People's Republic of China in 1949. Following the Chinese imperial tradition of using the sovereign's era name and year of reign, official ROC documents use the Republic system of numbering years in which the first year was 1912, the year of the establishment of the Republic of China. Months and days are numbered according to the Gregorian calendar; the Gregorian calendar was adopted by the nascent Republic of China effective 1 January 1912 for official business, but the general populace continued to use the traditional Chinese calendar. The status of the Gregorian calendar was unclear between 1916 and 1921 while China was controlled by several competing warlords each supported by foreign colonial powers. From about 1921 until 1928 warlords continued to fight over northern China, but the Kuomintang or Nationalist government controlled southern China and used the Gregorian calendar.
After the Kuomintang reconstituted the Republic of China on 10 October 1928, the Gregorian calendar was adopted, effective 1 January 1929. The People's Republic of China has continued to use the Gregorian calendar since 1949. Despite the adoption of the Gregorian calendar, the numbering of the years was still an issue; the Chinese imperial tradition was to use the emperor's era year of reign. One alternative to this approach was to use the reign of the half-historical, half-legendary Yellow Emperor in the third millennium BC to number the years. In the early 20th century, some Chinese Republicans began to advocate such a system of continuously numbered years, so that year markings would be independent of the Emperor's regnal name; when Sun Yat-sen became the provisional president of the Republic of China, he sent telegrams to leaders of all provinces and announced the 13th day of 11th Month of the 4609th year of the Yellow Emperor's reign to be the first year of the Republic of China. The original intention of the Minguo calendar was to follow the imperial practice of naming the years according to the number of years the Emperor had reigned, a universally recognizable event in China.
Following the establishment of the Republic, hence the lack of an Emperor, it was decided to use the year of the establishment of the current regime. This reduced the issue of frequent change in the calendar, as no Emperor ruled more than 61 years in Chinese history — the longest being the Kangxi Emperor, who ruled from 1662–1722; as Chinese era names are traditionally two characters long, 民國 is employed as an abbreviation of 中華民國. The first year, 1912, is called 民國元年 and 2010, the "99th year of the Republic" is 民國九十九年, 民國99年, or 99. Based on Chinese National Standard CNS 7648: Data Elements and Interchange Formats—Information Interchange—Representation of Dates and Times, year numbering may use the Gregorian system as well as the ROC era. For example, 3 May 2004 may be written 2004-05-03 or ROC 93-05-03; the ROC era numbering happens to be the same as the numbering used by the Juche calendar of North Korea, because its founder, Kim Il-sung, was born in 1912. The years in Japan's Taishō period coincide with those of the ROC era.
In addition to the ROC's Minguo calendar, Taiwanese continue to use the lunar Chinese calendar for certain functions such as the dates of many holidays, the calculation of people's ages, religious functions. The use of the ROC era system extends beyond official documents. Misinterpretation is more in the cases when the prefix is omitted. There have been legislative proposals by pro-Taiwan Independence political parties, such as the Democratic Progressive Party to abolish the Republican calendar in favor of the Gregorian calendar. To convert any Gregorian calendar year between 1912 and the current year to Minguo calendar, 1912 needs to be subtracted from the year in question 1 added. East Asian age reckoning Public holidays in Taiwan
X87 is a floating-point-related subset of the x86 architecture instruction set. It originated as an extension of the 8086 instruction set in the form of optional floating-point coprocessors that worked in tandem with corresponding x86 CPUs; these microchips had names ending in "87". This was known as the NPX. Like other extensions to the basic instruction set, x87 instructions are not needed to construct working programs, but provide hardware and microcode implementations of common numerical tasks, allowing these tasks to be performed much faster than corresponding machine code routines can; the x87 instruction set includes instructions for basic floating-point operations such as addition and comparison, but for more complex numerical operations, such as the computation of the tangent function and its inverse, for example. Most x86 processors since the Intel 80486 have had these x87 instructions implemented in the main CPU, but the term is sometimes still used to refer to that part of the instruction set.
Before x87 instructions were standard in PCs, compilers or programmers had to use rather slow library calls to perform floating-point operations, a method, still common in embedded systems. The x87 registers form an 8-level deep non-strict stack structure ranging from ST to ST with registers that can be directly accessed by either operand, using an offset relative to the top, as well as pushed and popped. There are instructions to push and pop values on top of this stack; the non-strict stack model allows binary operations to use ST together with a direct memory operand or with an explicitly specified stack register, ST, in a role similar to a traditional accumulator. This can be reversed on an instruction-by-instruction basis with ST as the unmodified operand and ST as the destination. Furthermore, the contents in ST can be exchanged with another stack register using an instruction called FXCH ST; these properties make the x87 stack usable as seven addressable registers plus a dedicated accumulator.
This is applicable on superscalar x86 processors, where these exchange instructions are optimized down to a zero clock penalty by using one of the integer paths for FXCH ST in parallel with the FPU instruction. Despite being natural and convenient for human assembly language programmers, some compiler writers have found it complicated to construct automatic code generators that schedule x87 code effectively; such a stack-based interface can minimize the need to save scratch variables in function calls compared with a register-based interface The x87 provides single-precision, double-precision and 80-bit double-extended precision binary floating-point arithmetic as per the IEEE 754-1985 standard. By default, the x87 processors all use 80-bit double-extended precision internally. A given sequence of arithmetic operations may thus behave differently compared to a strict single-precision or double-precision IEEE 754 FPU; as this may sometimes be problematic for some semi-numerical calculations written to assume double precision for correct operation, to avoid such problems, the x87 can be configured using a special configuration/status register to automatically round to single or double precision after each operation.
Since the introduction of SSE2, the x87 instructions are not as essential as they once were, but remain important as a high-precision scalar unit for numerical calculations sensitive to round-off error and requiring the 64-bit mantissa precision and extended range available in the 80-bit format. Clock cycle counts for examples of typical x87 FPU instructions; the A... B notation covers timing variations dependent on transient pipeline status and the arithmetic precision chosen; the L → H notation depicts values corresponding to the lowest and the highest maximal clock frequencies that were available. * An effective zero clock delay is possible, via superscalar execution. § The 5 MHz 8087 was the original x87 processor. Compared to typical software-implemented floating-point routines on an 8086, the factors would be larger by another factor of 10. Companies that have designed or manufactured floating-point units compatible with the Intel 8087 or models include AMD, Chips and Technologies, Fujitsu, Harris Semiconductor, IBM, IDT, IIT, LC Technology, National Semiconductor, NexGen, Rise Technology, ST Microelectronics, Texas Instruments, Transmeta, ULSI (the Math·Co copr
The traditional China calendar, or Former Calendar, Traditional Calendar or Lunar Calendar, is a lunisolar calendar which reckons years and days according to astronomical phenomena. It is defined by GB/T 33661-2017, "Calculation and promulgation of the Chinese calendar", issued by the Standardisation Administration of China on 12 May 2017. Although modern day China uses the Gregorian calendar, the traditional Chinese calendar governs holidays in China and in overseas Chinese communities, it lists the dates of traditional Chinese holidays and guides people in selecting auspicious days for weddings, moving, or starting a business. Like Chinese characters, variants of this calendar are used in different parts of the Chinese cultural sphere. Korea and the Ryukyu Islands adopted the calendar, it evolved into Korean and Ryukyuan calendars; the main difference from the traditional Chinese calendar is the use of different meridians, which leads to some astronomical events—and calendar events based on them—falling on different dates.
The traditional Japanese calendar derived from the Chinese calendar, but its official use in Japan was abolished in 1873 as part of reforms after the Meiji Restoration. Calendars in Mongolia and Tibet have absorbed elements of the traditional Chinese calendar, but are not direct descendants of it. Days begin and end at midnight, months begin on the day of the new moon. Years begin on the second new moon after the winter solstice. Solar terms govern the end of each month. Written versions in ancient China included stems and branches of the year and the names of each month, including leap months as needed. Characters indicated whether a month was short; the traditional Chinese calendar was developed between 771 and 476 BC, during the Spring and Autumn period of the Eastern Zhou dynasty. Before the Zhou dynasty, solar calendars were used. One version of the solar calendar is the five-elements calendar. A 365-day year was divided into five phases of 73 days, with each phase corresponding to a Day 1 Wu Xing element.
A phase began followed by six 12-day weeks. Each phase consisted of two three-week months. Years began followed by a bǐngzǐ day and a 72-day fire phase. Other days were tracked using the Yellow River Map. Another version is a four-quarters calendar. Weeks were ten days long, with one month consisting of three weeks. A year had 12 months, with a ten-day week intercalated in summer as needed to keep up with the tropical year; the 10 Heavenly Stems and 12 Earthly Branches were used to mark days. A third version is the balanced calendar. A year was 365.25 days, a month was 29.5 days. After every 16th month, a half-month was intercalated. According to oracle bone records, the Shang dynasty calendar was a balanced calendar with 12 to 14 months in a year; the first lunisolar calendar was the Zhou calendar, introduced under the Zhou dynasty. This calendar set the beginning of the year at the day of the new moon before the winter solstice, it set the shàngyuán as the winter solstice of a dīngsì year, making the year it was introduced around 2,758,130.
Several competing lunisolar calendars were introduced by states fighting Zhou control during the Warring States period. The state of Lu issued its own Lu calendar. Jin issued the Xia calendar in AD 102, with a year beginning on the day of the new moon nearest the March equinox. Qin issued the Zhuanxu calendar, with a year beginning on the day of the new moon nearest the winter solstice. Song's Yin calendar began its year on the day of the new moon after the winter solstice; these calendars are known as the six ancient calendars, or quarter-remainder calendars, since all calculate a year as 365 1⁄4 days long. Months begin on the day of the new moon, a year has 12 or 13 months. Intercalary months are added to the end of the year; the Qiang and Dai calendars are modern versions of the Zhuanxu calendar, used by mountain peoples. After Qin Shi Huang unified China under the Qin dynasty in 221 BC, the Qin calendar was introduced, it followed most of the rules governing the Zhuanxu calendar, but the month order was that of the Xia calendar.
The intercalary month, known as the second Jiǔyuè, was placed at the end of the year. The Qin calendar was used into the Han dynasty. Emperor Wu of Han r. 141 – 87 BC introduced reforms halfway through his reign. His Taichu Calendar defined a solar year as 365 385⁄1539 days, the lunar month was 29 43⁄81 days; this calendar introduced the 24 solar terms. Solar terms were paired, with the 12 combined periods known as climate terms; the first solar term of the period was known as a pre-climate, the second was a mid-climate. Months were named for the mid-climat
The 6th century is the period from 501 to 600 in line with the Julian calendar in the Common Era. In the West, the century marks the beginning of the Middle Ages; the collapse of the Western Roman Empire late in the previous century left Europe fractured into many small Germanic kingdoms competing fiercely for land and wealth. From the upheaval the Franks rose to prominence and carved out a sizeable domain covering much of modern France and Germany. Meanwhile, the surviving Eastern Roman Empire began to expand under Emperor Justinian, who recaptured North Africa from the Vandals and attempted to recover Italy as well, in the hope of reinstating Roman control over the lands once ruled by the Western Roman Empire. In its second Golden Age, the Sassanid Empire reached the peak of its power under Khosrau I in the 6th century; the classical Gupta Empire of Northern India overrun by the Huna, ended in the mid-6th century. In Japan, the Kofun period gave way to the Asuka period. After being divided for more than 150 years among the Southern and Northern Dynasties, China was reunited under the Sui Dynasty toward the end of the 6th century.
The Three Kingdoms of Korea persisted throughout the century. The Göktürks became a major power in Central Asia after defeating the Rouran. In the Americas, Teotihuacan began to decline in the 6th century after having reached its zenith between AD 150 and 450. Classic Period of the Maya civilization in Central America. Early 6th century – Ah Suytok Tutul Xiu founds Uxmal. Early 6th century – Archangel Michael, panel of a diptych from the court workshop at Constantinople, is made, it is now kept at London. Early 6th century – Page with Rebecca at the Well, from "Book of Genesis" made in Syria or Palestine, is made, it is now kept at Vienna. By 6th century – Shilpa Shastras is written. Early 6th century – first academy of the east the Academy of Gundeshapur founded in Iran by Khosrau I of Persia. Early 6th century – Irish colonists and invaders, the Scots, began migrating to Caledonia. Migration from south-west Britain to Brittany. Early 6th century – Glendalough monastery, Wicklow Ireland founded on St. Kevin.
Many similar foundations in Ireland and Wales. Early 6th century – Zen Buddhism enters Vietnam from China. Early 6th century – Haniwa, from Kyoto, is made during the Kofun period Early 6th century – Basilica of Sant'Apollinare in Classe's apse's mosaic is completed. 502: Chinese annals mentioned the existence of the Buddhist Kingdom, Kanto Lim in South Sumatra in the neighborhood of present-day Palembang. 507: Battle of Vouillé 518: Eastern Roman Emperor Anastasius I dies and is succeeded by Justin I. 522: Byzantines obtain silkworm eggs and begin silkworm cultivation c. 524: Boethius writes his Consolation of Philosophy. 525: Having settled in Rome c. 500, Scythian monk Dionysius Exiguus invents the Anno Domini era calendar based on the estimated birth year of Jesus Christ. 527: Justinian I succeeds Justin I as Emperor of the Eastern Roman Empire. 529: Saint Benedict of Nursia founds the monastery of Monte Cassino in Italy. 532: Nika riots in Constantinople. They are put down a week by Belisarius and Mundus.
535: Postulated volcanic eruption in the tropics which causes several years of abnormally cold weather, resulting in mass famine in the Northern Hemisphere. 537: Battle of Camlann, final battle of legendary King Arthur. 541–542: First pandemic of bubonic plague hits Constantinople and the rest of Byzantine Empire. 543/544: One of Justinian's edict leads to the Three-Chapter Controversy 545: Nubian Kingdom of Nobatia converts to Christianity. Mid-6th century – Cassiodorus founds a cenobitic monastery and scriptorium at Vivarium in Italy Mid-6th century – Buddhist Jataka stories are translated into Persian by order of the Zoroastrian king Khosrau. Mid-6th century – Cave-Temple of Shiva at Elephanta Caves, India, is built. Post-Gupta period. Mid-6th century – Eternal Shiva, rock-cut relief in the Cave-Temple of Shiva at Elephanta Caves, is made Second half of 6th century – Virgin and Child with Saints and Angels, icon, is made, it is now kept at Egypt. 550: Kingdom of Funan dies out. 551: Bumin Khagan founded the Turkic Khaganate in the Central Asia 552: Buddhism introduced to Japan from Baekje during the Asuka period.
553: Second Council of Constantinople 554: Eviction of the Ostrogoths from Rome, the re-unification of all Italy under Byzantine rule. 561 to 592: Buddhist monk Jnanagupta translates 39 sutras from Sanskrit to Chinese. 563: The monastery on Iona is founded by St. Columba. 566: Birth of Lǐ Yuān, founder of the Tang Dynasty and Emperor of China under the name of Gaozu 568: Lombards invade Italy and establish a federation of dukedoms under a king. 569: Nubian kingdom of Alodia converts to Christianity. 569: Nubian kingdom of Makuria converts to Christianity. 570: Birth of the Islamic prophet, Muhammad. 574: The Byzantine empire is invaded by various Slavs, the Balkans are plundered by the Slavs. 577: China's Chen Dynasty invents matches. 579–590: Reign of Persian Shah Hormizd IV. 582–602: Reign of Byzantine Emperor Maurice. 585: Suebian Kingdom conquered by Visigoths in Spain. 587: Reccared, king of the Visigoths in Spain, converts to Catholicism. 588: Shivadeva ascends the throne of the Lichchhavi dynasty in Nepal.
589: Third Council of Toledo adds the "filioque" clause to the Nicene Creed in Spain. 589: China reunified under the Sui Dynasty. 590: Gregory the Great succeeds Pope Pelagius II as the 64th pope. 594: Beginning of the Bengali Calendar or
The Byzantine calendar called "Creation Era of Constantinople" or "Era of the World", was the calendar used by the Eastern Orthodox Church from c. 691 to 1728 in the Ecumenical Patriarchate. It was the official calendar of the Byzantine Empire from 988 to 1453, of Kievan Rus' and Russia from c. 988 to 1700. Since "Byzantine" is a historiographical term, the original name uses the noun "Roman" as it was how the Eastern Roman Empire continued calling itself; the calendar was based on the Julian calendar, except that the year started on 1 September and the year number used an Anno Mundi epoch derived from the Septuagint version of the Bible. It placed the date of creation at 5509 years before the Incarnation, was characterized by a certain tendency, a tradition among Jews and early Christians to number the years from the calculated foundation of the world, its Year One, marking the supposed date of creation, was September 1, 5509 BC, to August 31, 5508 BC. It is not known when; the first appearance of the term is in the treatise of a certain "monk and priest", who mentions all the main variants of the "World Era" in his work.
Georgios argues that the main advantage of the World era is the common starting point of the astronomical lunar and solar cycles, of the cycle of indictions, the usual dating system in Byzantium since the 6th century. He already regards it as the most convenient for the Easter computus. Complex calculations of the 19-year lunar and 28-year solar cycles within this world era allowed scholars to discover the cosmic significance of certain historical dates, such as the birth or the crucifixion of Jesus; this date underwent minor revisions before being finalized in the mid-7th century, although its precursors were developed c. AD 412. By the second half of the 7th century, the Creation Era was known in Western Europe, at least in Great Britain. By the late 10th century around AD 988, when the era appears in use on official government records, a unified system was recognized across the Eastern Roman world; the era was calculated as starting on September 1, Jesus was thought to have been born in the year 5509 since the creation of the world.
Historical time was thus calculated from the creation, not from Christ's birth, as in the west after the Anno Domini system was adopted between 6th and 9th centuries. The Eastern Church avoided the use of the Anno Domini system of Dionysius Exiguus, since the date of Christ's birth was debated in Constantinople as late as the 14th century. Otherwise the Byzantine calendar was identical to the Julian Calendar except that: the names of the months were transcribed from Latin into Greek; the leap day of the Byzantine calendar was obtained in an identical manner to the bissextile day of the original Roman version of the Julian calendar, by doubling the sixth day before the calends of March, i.e. by doubling 24 February. The Byzantine World Era was replaced in the Orthodox Church by the Christian Era, utilized by Patriarch Theophanes I Karykes in 1597, afterwards by Patriarch Cyril Lucaris in 1626, formally established by the Church in 1728. Meanwhile, as Russia received Orthodox Christianity from Byzantium, she inherited the Orthodox Calendar based on the Byzantine Era.
After the collapse of the Byzantine Empire in 1453, the era continued to be used by Russia, which witnessed millennialist movements in Moscow in AD 1492. It was only in AD 1700 that the Byzantine World Era in Russia was changed to the Julian Calendar by Peter the Great, it still forms the basis of traditional Orthodox calendars up to today. September AD 2000 began the year 7509 AM; the earliest extant Christian writings on the age of the world according to the Biblical chronology are by Theophilus, the sixth bishop of Antioch from the Apostles, in his apologetic work To Autolycus, by Julius Africanus in his Five Books of Chronology. Both of these early Christian writers, following the Septuagint version of the Old Testament, determined the age of the world to have been about 5,530 years at the birth of Christ. Ben Zion Wacholder points out that the writings of the Church Fathers on this subject are of vital significance, in that through the Christian chronographers a window to the earlier Hellenistic biblical chronographers is preserved: An immense intellectual effort was expended during the Hellenistic period by both Jews and pagans to date creation, the flood, building of the Temple...
In the course of their studies, men such as Tatian of Antioch, Clement of Alexandria, Hippolytus of Rome
Ab urbe condita
Ab urbe condita, or Anno urbis conditæ abbreviated as AUC in either case, is a convention, used in antiquity and by classical historians to refer to a given year in Ancient Rome. Ab urbe condita means "from the founding of the City," while anno urbis conditæ means "in the year since the City's founding." Therefore, the traditional year of the foundation of Rome, 753 BC, would be written AUC 1, while AD 1 would be AUC 754. The foundation of the Empire in 27 BC would be AUC 727. Usage of the term was more common during the Renaissance, when editors sometimes added AUC to Roman manuscripts they published, giving the false impression that the convention was used in antiquity. In reality, the dominant method of identifying years in Roman times was to name the two consuls who held office that year. In late antiquity, regnal years were in use, as was the Diocletian era in Roman Egypt after AD 293, in the Byzantine Empire after AD 537, following a decree by Justinian; the traditional date for the founding of Rome, 21 April 753 BC, is due to Marcus Terentius Varro.
Varro may have used the consular list and called the year of the first consuls "ab urbe condita 245," accepting the 244-year interval from Dionysius of Halicarnassus for the kings after the foundation of Rome. The correctness of this calculation has not been confirmed. From the time of Claudius onward, this calculation superseded other contemporary calculations. Celebrating the anniversary of the city became part of imperial propaganda. Claudius was the first to hold magnificent celebrations in honor of the anniversary of the city, in AD 48, the eight hundredth year from the founding of the city. Hadrian and Antoninus Pius held similar celebrations, in AD 121, in AD 147 and AD 148, respectively. In AD 248, Philip the Arab celebrated Rome's first millennium, together with Ludi saeculares for Rome's alleged tenth sæculum. Coins from his reign commemorate the celebrations. A coin by a contender for the imperial throne, explicitly states "ear one thousand and first", an indication that the citizens of the empire had a sense of the beginning of a new era, a Sæculum Novum.
The Anno Domini year numbering was developed by a monk named Dionysius Exiguus in Rome in AD 525, as a result of his work on calculating the date of Easter. Dionysius did not use the AUC convention, but instead based his calculations on the Diocletian era; this convention had been in use since AD 293, the year of the tetrarchy, as it became impractical to use regnal years of the current emperor. In his Easter table, the year AD 532 was equated with the 248th regnal year of Diocletian; the table counted the years starting from the presumed birth of Christ, rather than the accession of the emperor Diocletian on 20 November AD 284, or as stated by Dionysius: "sed magis elegimus ab incarnatione Domini nostri Jesu Christi annorum tempora praenotare". Blackburn and Holford-Strevens review interpretations of Dionysius which place the Incarnation in 2 BC, 1 BC, or AD 1, it has been calculated that the year AD 1 corresponds to AUC 754, based on the epoch of Varro. Thus, AUC 1 = 753 BC AUC 753 = 1 BC AUC 754 = AD 1 AUC 1000 = AD 247 AUC 1229 = AD 476 AUC 2206 = AD 1453 AUC 2753 = AD 2000 AUC 2772 = AD 2019 List of Latin phrases