Roman Empire

==Geography and demography==
{{Main|Demography of the Roman Empire|Borders of the Roman Empire}}
{{Further|Classical demography}}

The Roman Empire was [[List of largest empires|one of the largest]] in history, with contiguous territories throughout Europe, North Africa, and the Middle East.{{Sfnp|Kelly|2007|p=3}} The Latin phrase ''imperium sine fine'' ("empire without end"{{Sfnp|Nicolet|1991|p=29}}) expressed the ideology that neither time nor space limited the Empire. In [[Virgil]]'s ''[[Aeneid]]'', limitless empire is said to be granted to the Romans by [[Jupiter (mythology)|Jupiter]].<ref>{{Harvp|Nicolet|1991|p=29}}; {{Harvp|Virgil|p=1.278}}; {{Cite book |last=Mattingly |first=David J. |title=Imperialism, Power, and Identity: Experiencing the Roman Empire |date=2011 |publisher=Princeton University Press |page=15 |author-link=David Mattingly (archaeologist)}}; {{Citation |last=Moretti |first=G |chapter=The Other World and the 'Antipodes': The Myth of Unknown Countries between Antiquity and the Renaissance |date=1993 |title=The Classical Tradition and the Americas: European Images of the Americas |editor-last=de Gruyter |editor-first=Walter |page=257}}; {{Cite book |last=Southern |first=Pat |title=The Roman Empire from Severus to Constantine |date=2001 |publisher=Routledge |isbn=978-0-415-23943-1 |pages=14–16 |author-link=Pat Southern}}</ref> This claim of universal dominion was renewed when the Empire came under Christian rule in the 4th century.{{Efn|[[Prudentius]] (348–413) in particular Christianizes the theme in his poetry.<ref>{{Cite book |last=Mastrangelo |first=Marc |title=The Roman Self in Late Antiquity: Prudentius and the Poetics of the Soul |date=2008 |publisher=Johns Hopkins University Press |pages=73, 203}}</ref> [[St. Augustine]], however, distinguished between the secular and eternal "Rome" in ''[[De Civitate Dei|The City of God]].'' See also {{Citation |last=Fears |first=J. Rufus |chapter=The Cult of Jupiter and Roman Imperial Ideology |date=1981 |title=Aufstieg und Niedergang der römischen Welt |volume=II |issue=17.1 |author-link=J. Rufus Fears |page=136}}, on how Classical Roman ideology influenced Christian Imperial doctrine, {{Citation |last=Bang |first=Peter Fibiger |chapter=The King of Kings: Universal Hegemony, Imperial Power, and a New Comparative History of Rome |date=2011 |title=The Roman Empire in Context: Historical and Comparative Perspectives |publisher=John Wiley & Sons}} and the Greek concept of globalism (''[[ecumene|oikouménē]]'').}} In addition to annexing large regions, the Romans directly altered their geography, for example [[Deforestation during the Roman period|cutting down entire forests]].<ref>{{Cite book |last=Mosley |first=Stephen |url=https://archive.org/details/environmentworld00mosl_888 |title=The Environment in World History |date=2010 |publisher=Routledge |page=[https://archive.org/details/environmentworld00mosl_888/page/n44 35] |url-access=limited}}</ref>

[[Campaign history of the Roman military|Roman expansion]] was mostly accomplished under the [[Roman Republic|Republic]], though parts of northern Europe were conquered in the 1st century, when Roman control in Europe, Africa, and Asia was strengthened. Under [[Augustus]], a "global map of the known world" was displayed for the first time in public at Rome, coinciding with the creation of the most comprehensive [[political geography]] that survives from antiquity, the ''[[Geographica|Geography]]'' of [[Strabo]].{{Sfnp|Nicolet|1991|pp=7, 8}} When Augustus died, the account of his achievements (''[[Res Gestae Divi Augusti|Res Gestae]]'') prominently featured the geographical cataloguing of the Empire.{{Sfnp|Nicolet|1991|pp=9, 16}} Geography alongside meticulous written records were central concerns of [[#Central government|Roman Imperial administration]].{{Sfnp|Nicolet|1991|pp=10, 11}}

[[File:Milecastle 39 on Hadrian's Wall.jpg|thumb|A segment of the ruins of [[Hadrian's Wall]] in northern England, overlooking [[Crag Lough]]]]
The Empire reached its largest expanse under [[Trajan]] ({{R.|98|117}}),{{Sfnp|Southern|2001|pp=14–16}} encompassing 5 million square kilometres.<ref name="size"/><ref name="East-West"/> The traditional population estimate of {{Nowrap|55–60 million}} inhabitants{{Sfnp|Kelly|2007|p=1}} accounted for between one-sixth and one-fourth of the world's total population{{Sfnp|Morris|Scheidel|2009|p=184}} and made it the most populous unified political entity in the West until the mid-19th century.<ref>{{Cite journal |last=Goldsmith |first=Raymond W. |date=2005 |title=An Estimate of the Size And Structure of the National Product of the Early Roman Empire |journal=Review of Income and Wealth |volume=30 |issue=3 |doi=10.1111/j.1475-4991.1984.tb00552.x |pages=263–288}}</ref> Recent [[Classical demography#Demography of the Roman Empire|demographic studies]] have argued for a population peak from {{Nowrap|70 million}} to more than {{Nowrap|100 million}}.<ref name="Population and demography">{{Cite web |last=Scheidel |first=Walter |date=April 2006 |title=Population and demography |url=http://www.princeton.edu/~pswpc/pdfs/scheidel/040604.pdf |website=Princeton/Stanford Working Papers in Classics |page=9 |access-date=25 July 2009 |archive-date=13 November 2018 |archive-url=https://web.archive.org/web/20181113015918/http://www.princeton.edu/~pswpc/pdfs/scheidel/040604.pdf |url-status=live }}; {{Cite journal |last1=Hanson |first1=J. W. |last2=Ortman |first2=S. G. |date=2017 |title=A systematic method for estimating the populations of Greek and Roman settlements |journal=Journal of Roman Archaeology |language=en |volume=30 |doi=10.1017/S1047759400074134 |pages=301–324|s2cid=165770409 }}</ref> Each of the three largest cities in the Empire – Rome, [[Alexandria]], and [[Antioch]] – was almost twice the size of any European city at the beginning of the 17th century.{{Sfnp|Boardman|2000|p=721}}

As the historian [[Christopher Kelly (historian)|Christopher Kelly]] described it:

{{Blockquote|Then the empire stretched from [[Hadrian's Wall]] in drizzle-soaked [[northern England]] to the sun-baked banks of the [[Euphrates]] in Syria; from the great [[Rhine]]–[[Danube]] river system, which snaked across the fertile, flat lands of Europe from the [[Low Countries]] to the [[Black Sea]], to the rich plains of the North African coast and the luxuriant gash of the [[Nile Valley]] in Egypt. The empire completely circled the [[Mediterranean]]&nbsp;... referred to by its conquerors as ''[[Mare Nostrum|mare nostrum]]''—'our sea'.{{Sfnp|Kelly|2007|p=1}}}}

Trajan's successor [[Hadrian]] adopted a policy of maintaining rather than expanding the empire. Borders (''fines'') were marked, and the frontiers (''[[Limes (Roman Empire)|limites]]'') patrolled.{{Sfnp|Southern|2001|pp=14–16}} The most heavily fortified borders were the most unstable.<ref name="Hekster">{{Cite journal |last1=Hekster |first1=Olivier |last2=Kaizer |first2=Ted |date=16–19 April 2009 |title=Preface |publisher=Brill |journal=Frontiers in the Roman World: Proceedings of the Ninth Workshop of the International Network Impact of Empire |page=viii}}</ref> [[Hadrian's Wall]], which separated the Roman world from what was perceived as an ever-present [[barbarian]] threat, is the primary surviving monument of this effort.<ref>{{Cite book |title=Cambridge Illustrated History of the Roman World |date=2003 |publisher=Ivy Press |editor-last=Woolf |editor-first=Greg |page=340}}; {{Cite book |last=Opper |first=Thorsten |title=Hadrian: Empire and Conflict |date=2008 |publisher=Harvard University Press |page=64}}; {{Cite book |last=Fields |first=Nic |title=Hadrian's Wall AD 122–410, which was, of course, at the bottom of Hadrian's garden |date=2003 |publisher=Osprey Publishing |page=35}}</ref>