| common_name = Roman Empire
| continent=Eurasia |region=Mediterranean |status=Empire
| life_span = }}
– 1453 }}
| p1=Roman Republic |image_p1=
| s1=Western Roman Empire |image_s1=
| s2=Eastern Roman Empire |image_s2=
| image_coat=Augustus Aureus infobox version.png |coa_size=170px |symbol_type=''Aureus'' of Augustus, the first Roman Emperor.
| image_map = Roman Empire Trajan 117AD.png
| image_map_caption = The Roman Empire in 117 AD, at its greatest extent.〔Bennett, J. ''Trajan: Optimus Princeps''. 1997. Fig. 1. Regions east of the Euphrates river were held only in the years 116–117.〕
| capital =
Mediolanum (286-402, Western)
Ravenna (402–476, Western)
Nicomedia (286-330, Eastern)
Constantinople (330-1453, Eastern)
| common_languages =
| religion =
| government_type = Mixed, functionally absolute monarchy
| title_leader = Emperor
| year_leader1 = |leader1 = Augustus
| year_leader2 = 98–117 |leader2 = Trajan
| year_leader3 = 284–305 |leader3 = Diocletian
| year_leader4 = 306–337 |leader4 = Constantine I
| year_leader5 = 379–395 |leader5 = Theodosius I
| legislature = Senate
| era = Classical era to Late Antiquity
| date_pre = 32–30 BC |event_pre = Final War of the
| year_start = 30–2 BC |event_start = Empire established
| date_event1 = AD 117 |event1 = Empire at its
| date_event2 = 330 |event2 = Constantinople
| date_event3 = 395 |event3 =
| year_end = 476 |event_end = Fall of the (Western) Roman Empire
| stat_year1 = 25 BC〔John D. Durand, ''Historical Estimates of World Population: An Evaluation'', 1977, pp. 253–296.〕 |stat_area1 = 2750000 |stat_pop1 = 56800000
| stat_year2 = 117 AD 〔|stat_area2 = 5000000 |stat_pop2 =
| stat_year3 = 390 AD 〔 |stat_area3 = 4400000 |stat_pop3 =
| currency = Sestertius, Aureus, Solidus, Nomisma
| footnotes =
The Roman Empire ((ラテン語:Imperium Rōmānum); Ancient and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr. ) was the post-Roman Republic period of the ancient Roman civilization, characterized by government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome extended and between c. 100 BC- 400 AD was the largest city in the world, whereas Constantinople (New Rome) retained the first position around 500 AD,〔(a) (Ian Morris, ''Social Development'', Stanford University, October 2010. ) This contains supporting materials for the following book: (b) Ian Morris, ''Why the West Rules—For Now'', New York: Farrar, Straus and Giroux, 2010. ISBN 978-0-374-29002-3.〕 whilst the Empire's populace grew into an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time).〔an average of figures from different sources as listed at the US Census Bureau's (Historical Estimates of World Population ); see also
*Kremer, Michael (1993). "Population Growth and Technological Change: One Million B.C. to 1990" in ''The Quarterly Journal of Economics'' 108(3): 681–716.〕 The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt. Octavian's power was now unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title ''Augustus'', effectively marking the end of the Roman Republic.
The imperial successor to the Republic lasted approximately 1400 years. The first two centuries of the Empire's existence were a period of unprecedented political stability and prosperity known as the ''Pax Romana'', or "Roman Peace". Following Octavian's victory, the size of the Empire was dramatically increased. After the assassination of Caligula in 41, the Senate briefly considered restoring the republic, but the Praetorian Guard proclaimed Claudius Emperor instead. Under Claudius, the Empire invaded Britannia, its first major expansion since Augustus. After Claudius' successor, Nero, committed suicide in 68, the Empire suffered a period of brief civil wars, as well as a concurrent major rebellion in Judea, during which four different legionary generals were proclaimed Emperor. Vespasian emerged triumphant in 69, establishing the Flavian dynasty, before being succeeded by his son Titus, who opened the Colosseum shortly after the eruption of Mt. Vesuvius. His short reign was followed by the long reign of his brother Domitian, who was eventually assassinated. The Senate then appointed the first of the Five Good Emperors. The Empire reached its greatest extent under Trajan, the second in this line.
A period of increasing trouble and decline began with the reign of Commodus. Commodus' assassination in 192 triggered the Year of the Five Emperors, of which Septimius Severus emerged victorious. The assassination of Alexander Severus in 235 led to the Crisis of the Third Century in which 26 men were declared Emperor by the Roman Senate over a fifty-year period. It was not until the reign of Diocletian that the Empire was fully stabilized with the introduction of the Tetrarchy, which saw four Emperors rule the Empire at once. This arrangement was ultimately unsuccessful, leading to a civil war that was finally ended by Constantine I, who defeated his rivals and became the sole ruler of the Empire. Constantine subsequently shifted the capital to Byzantium, which was renamed Constantinople in his own honor. It remained the capital of the east until its demise. Constantine also adopted Christianity which later became the official state religion of the Empire. This eastern part of the empire (known later as the Byzantine Empire) remained one of the leading powers in the world alongside its arch-rival the Sassanid Persian Empire, which had inherited a centuries-old Roman-Persian conflict from its predecessor the Parthians.〔Norman A. Stillman ''The Jews of Arab Lands'' pp 22 Jewish Publication Society, 1979 ISBN 0827611552〕〔International Congress of Byzantine Studies ''Proceedings of the 21st International Congress of Byzantine Studies, London, 21–26 August 2006, Volumes 1–3'' pp 29. Ashgate Pub Co, 30 sep. 2006 ISBN 075465740X〕〔J.H. Breasted ''Ancient Times a History of the Early World'' pp 675. Рипол Классик ISBN 117400312X〕 Following the death of Theodosius I, the last Emperor to rule a united Empire, the dominion of the Empire was gradually eroded by abuses of power, civil wars, barbarian migrations and invasions, military reforms and economic depression. The Sack of Rome in 410 by the Visigoths and again in 455 by the Vandals accelerated the Western Empire's decay, while the deposition of the Emperor Romulus Augustulus in 476 by Odoacer is generally accepted to mark the end of the Empire in the west. However, with Romulus Augustulus technically being a usurper, the Western part of the empire only truly legally ceased to exist upon the death of the true Emperor Julius Nepos in 480. The Eastern Roman Empire endured for another thousand years, eventually falling to the Ottoman Turks in 1453.
The Roman Empire was among the most powerful economic, cultural, political and military forces in the world of its time. It was the largest empire of the classical antiquity period, and one of the largest empires in world history. At its height under Trajan, it covered 5 million square kilometers〔〔 and held sway over some 70 million people, at that time 21% of the world's entire population. The longevity and vast extent of the Empire ensured the lasting influence of Latin and Greek language, culture, religion, inventions, architecture, philosophy, law and forms of government on the Empire's descendants. Throughout the European medieval period, attempts were even made to establish successors to the Roman Empire, including the Crusader state, the Empire of Romania and the Holy Roman Empire. By means of European expansionism through the Spanish, French, Portuguese, Dutch, Italian, Russian, German, British and Belgian Empires, Greco-Roman culture was spread on a worldwide scale, playing a significant role in the development of the modern world.
(詳細はItaly until the 3rd century BC. Then, it was an "empire" long before it had an Emperor.〔Christopher Kelly, ''The Roman Empire: A Very Short Introduction'' (Oxford University Press, 2006), p. 4ff.; Claude Nicolet, ''Space, Geography, and Politics in the Early Roman Empire'' (University of Michigan Press, 1991, originally published in French 1988), pp. 1, 15; T. Corey Brennan, ''The Praetorship in the Roman Republic'' (Oxford University Press, 2000), p. 605 ''et passim''; Clifford Ando, "From Republic to Empire", in ''The Oxford Handbook of Social Relations in the Roman World'' (Oxford University Press, pp. 39–40.〕 The Roman Republic was not a nation-state in the modern sense, but a network of towns left to rule themselves (though with varying degrees of independence from the Roman Senate) and provinces administered by military commanders. It was ruled, not by Emperors, but by annually elected magistrates (Roman Consuls above all) in conjunction with the Senate.〔Clifford Ando, "The Administration of the Provinces", in ''A Companion to the Roman Empire'' (Blackwell, 2010), p. 179.〕 For various reasons, the 1st century BC was a time of political and military upheaval, which ultimately led to rule by Emperors.〔Nicolet, ''Space, Geography, and Politics in the Early Roman Empire'', pp. 1, 15; Olivier Hekster and Ted Kaizer, preface to ''Frontiers in the Roman World. Proceedings of the Ninth Workshop of the International Network Impact of Empire (Durham, 16–19 April 2009)'' (Brill, 2011), p. viii; Andrew Lintott, ''The Constitution of the Roman Republic'' (Oxford University Press, 1999), p. 114; W. Eder, "The Augustan Principate as Binding Link," in ''Between Republic and Empire'' (University of California Press, 1993), p. 98.〕 The consuls' military power rested in the Roman legal concept of ''imperium'', which literally means "command" (though typically in a military sense).〔John Richardson, "''Fines provinciae''", in ''Frontiers in the Roman World'', p. 10.〕 Occasionally, successful consuls were given the honorary title ''Imperator'' (commander), and this is the origin of the word "Emperor" (and "Empire") since this title (among others) was always bestowed to the early Emperors upon their accession.〔Richardson, "''Fines provinciae''", in ''Frontiers in the Roman World'', pp. 1–2.〕
Rome suffered a long series of internal conflicts, conspiracies and civil wars from the late second century BC onwards, while greatly extending its power beyond Italy. Towards the end of this period, in 44 BC, Julius Caesar was briefly perpetual dictator before being assassinated. The faction of his assassins was driven from Rome and defeated at the Battle of Phillipi in 42 BC by an army led by Mark Antony and Caesar's adopted son Octavian. Antony and Octavian's division of the Roman world between themselves did not last and Octavian's forces defeated those of Antony and Cleopatra at the Battle of Actium in 31 BC. In 27 BC the Senate and People of Rome made Octavian ''princeps'' ("first citizen") with proconsular ''imperium'', thus beginning the Principate (the first epoch of Roman imperial history, usually dated from 27 BC to AD 284), and gave him the name Augustus ("the venerated"). Though the old constitutional machinery remained in place, Augustus came to predominate it. Although the Republic stood in name, contemporaries of Augustus knew it was just a veil and that Augustus had all meaningful authority in Rome.〔Ronald Syme,''The Roman Revolution'', Oford: Oxford University Press, 1939, 3–4.〕 Since his rule ended a century of civil wars, and began an unprecedented period of peace and prosperity, he was so loved that he came to hold the power of a monarch ''de facto'' if not ''de jure''. During the years of his rule, a new constitutional order emerged (in part organically and in part by design), so that, upon his death, this new constitutional order operated as before when Tiberius was accepted as the new Emperor. The 200 years that began with Augustus' rule is traditionally regarded as the Pax Romana ("Roman Peace"). During this period, the cohesion of the Empire was furthered by a degree of social stability and economic prosperity that Rome had never before experienced. Uprisings in the provinces were infrequent, but put down "mercilessly and swiftly" when they occurred.〔Mary T. Boatwright, ''Hadrian and the Cities of the Roman Empire'' (Princeton University Press, 2000), p. 4.〕 The sixty years of Jewish–Roman wars in the second half of the first century and the first half of the 2nd century were exceptional in their duration and violence.〔Yaron Z. Eliav, "Jews and Judaism 70–429 CE", in ''A Companion to the Roman Empire'' (Blackwell, 2010), p. 571.〕
The success of Augustus in establishing principles of dynastic succession was limited by his outliving a number of talented potential heirs: the Julio-Claudian dynasty lasted for four more emperors — Tiberius, Caligula, Claudius and Nero — before it yielded in 69 AD to the strife-torn Year of Four Emperors, from which Vespasian emerged as victor. Vespasian became the founder of the brief Flavian dynasty, to be followed by the Nerva–Antonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius and the philosophically inclined Marcus Aurelius. In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in 180 AD marked the descent "from a kingdom of gold to one of rust and iron"〔Dio Cassius (72.36.4 ), Loeb edition translated E. Cary〕—a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire.
In 212, during the reign of Caracalla, Roman citizenship was granted to all freeborn inhabitants of the Empire. But despite this gesture of universality, the Severan dynasty was tumultuous — an emperor's reign was ended routinely by his murder or execution — and, following its collapse, the Roman Empire was engulfed by the Crisis of the Third Century, a period of invasions, civil strife, economic disorder, and plague.〔Brown, P., The World of Late Antiquity, London 1971, p. 22.〕 In defining historical epochs, this crisis is sometimes viewed as marking the transition from Classical Antiquity to Late Antiquity. Aurelian (reigned 270–275) brought the Empire back from the brink and stabilized it. Diocletian completed the work of fully restoring the empire, but declined the role of ''princeps'' and became the first emperor to be addressed regularly as ''domine'', "master" or "lord".〔Adrian Goldsworth, ''How Rome Fell: Death of a Superpower'' (Yale University Press, 2009), pp. 405–415.〕 This marked the end of the Principate, and the beginning of the Dominate. Diocletian's reign also brought the Empire's most concerted effort against the perceived threat of Christianity, the "Great Persecution". The state of absolute monarchy that began with Diocletian endured until the fall of the Eastern Roman Empire in 1453.
Diocletian divided the empire into four regions, each ruled by a separate Emperor (the Tetrarchy).〔Potter, David. The Roman Empire at Bay. 296–98.〕 Confident that he fixed the disorders that were plaguing Rome, he abdicated along with his co-emperor, and the Tetrarchy soon collapsed. Order was eventually restored by Constantine, who became the first emperor to convert to Christianity, and who established Constantinople as the new capital of the eastern empire. During the decades of the Constantinian and Valentinian dynasties, the Empire was divided along an east–west axis, with dual power centers in Constantinople and Rome. The reign of Julian, who attempted to restore Classical Roman and Hellenistic religion, only briefly interrupted the succession of Christian emperors. Theodosius I, the last emperor to rule over both East and West, died in 395 AD after making Christianity the official religion of the Empire.〔Chester G. Starr, ''A History of the Ancient World, Second Edition.'' Oxford University Press, 1974. pp. 670–678.〕
The Western Roman Empire began to disintegrate in the early 5th century as Germanic migrations and invasions overwhelmed the capacity of the Empire to assimilate the migrants and fight off the invaders. The Romans were successful in fighting off all invaders, most famously Attila the Hun, though the Empire had assimilated so many Germanic peoples of dubious loyalty to Rome that the Empire started to dismember itself. Most chronologies place the end of the Western Roman Empire in 476, when Romulus Augustulus was forced to abdicate to the Germanic warlord Odoacer.〔Isaac Asimov (1989) ''Asimov's Chronology of the World,'' p. 110, New York, NY, USA: HarperCollins.〕 By placing himself under the rule of the Eastern Emperor, rather than naming himself Emperor (as other Germanic chiefs had done after deposing past Emperors), Odoacer ended the Western Empire by ending the line of Western Emperors.
The empire in the East — often known as the Byzantine Empire, but referred to in its time as the Roman Empire or by various other names — had a different fate. It survived for almost a millennium after the fall of its Western counterpart and became the most stable Christian realm during the Middle Ages. During the 6th century, Justinian briefly reconquered Northern Africa and Italy, but Roman possessions in the West were reduced to southern Italy and Sicily within a few years after Justinian's death.〔Duiker, 2001. page 347.〕 In the east, partially resulting from the destructive Plague of Justinian, the Romans were threatened by the rise of Islam, whose followers rapidly conquered the territories of Syria, Armenia and Egypt during the Byzantine-Arab Wars, and soon presented a direct threat to Constantinople.〔(The Byzantine Empire ) by Richard Hooker. Washington State University. Written 6 June 1999. Retrieved 8 April 2007.〕〔
〕 In the following century, the Arabs also captured southern Italy and Sicily.〔
〕 Slavic populations were also able to penetrate deep into the Balkans.
The Romans, however, managed to stop further Islamic expansion into their lands during the 8th century and, beginning in the 9th century, reclaimed parts of the conquered lands.〔Duiker, 2001. page 349.〕 In 1000 AD, the Eastern Empire was at its height: Basileios II reconquered Bulgaria and Armenia, culture and trade flourished.〔(Basil II (AD 976–1025) ) by Catherine Holmes. De Imperatoribus Romanis. Written 1 April 2003. Retrieved 22 March 2007.〕 However, soon after the expansion was abruptly stopped in 1071 with their defeat in the Battle of Manzikert. The aftermath of this important battle sent the empire into a protracted period of decline. Two decades of internal strife and Turkic invasions ultimately paved the way for Emperor Alexius I Comnenus to send a call for help to the Western European kingdoms in 1095.〔
The West responded with the Crusades, eventually resulting in the Sack of Constantinople by participants in the Fourth Crusade. The conquest of Constantinople in 1204 fragmented what remained of the Empire into successor states, the ultimate victor being that of Nicaea.〔Gibbon, Edward. ''History of the Decline and Fall of the Roman Empire''. (Chapter 61 ). Retrieved 11 April 2007.〕 After the recapture of Constantinople by Imperial forces, the Empire was little more than a Greek state confined to the Aegean coast. The Roman Empire finally collapsed when Mehmed II conquered Constantinople on 29 May, 1453.〔(Mehmet II ) by Korkut Ozgen. Theottomans.org. Retrieved 3 April 2007.〕
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