When is the Roman Empire shown on the map?

The border data draws the Roman Empire AD 1–394. The source samples borders at fixed dates, so a span can begin late or run on past the end.

How large was the Roman Empire?

At its greatest extent drawn on this map, the Roman Empire covered about 5.4 million km². That is the largest area the border data gives it across the years it is drawn, not necessarily its greatest extent in history.

Europe · Antiquity and the Roman world

Roman Empire

drawn on the map AD 1–394

The Roman Empire in its undivided phase ran from Augustus (Octavian), who became princeps in 27 BC after defeating Antony and Cleopatra at Actium (31 BC), to the death of Theodosius I in AD 395, after which the empire was permanently divided administratively between his sons. At its height under Trajan (AD 117) it stretched from Britain to Mesopotamia, ringing the Mediterranean (Mare Nostrum).

See it on the map → Wikipedia ↗

Shown on the map: AD 1–394
Peak area: 5.4M km²
Region: Europe

Overview

Government and institutions

The Augustan settlement (the Principate) preserved republican forms — Senate, consuls, assemblies — while concentrating real power in the princeps, who held imperium proconsulare maius and tribunicia potestas. The professional standing army (legions plus auxiliaries, c. 25–30 legions) was the backbone of power and frontier defence (the limes). A sophisticated system of provinces, roads, aqueducts, coinage, and law bound the empire together. Roman law — the Twelve Tables, praetorian edicts, and juristic writing — is among Rome's most enduring legacies.

Dynasties and turning points

The Julio-Claudians (to AD 68), the Flavians, the "Five Good Emperors" and the Nerva–Antonine peak, and the Severans gave way to the Crisis of the Third Century (235–284), a half-century of civil war, usurpation (including the breakaway Gallic and Palmyrene empires), plague, invasion, and debasement of the currency. Diocletian (r. 284–305) restructured the state with the Tetrarchy, price edicts, and administrative reform. Constantine the Great (r. 306–337) reunified the empire, founded Constantinople (330), and through the Edict of Milan (313) and his own patronage set Rome on the path to Christianisation, completed when Theodosius I made Nicene Christianity the state religion (Edict of Thessalonica, 380) and suppressed paganism. The economy rested on agriculture, slavery, taxation, and vast Mediterranean trade. The 395 division into Western and Eastern halves proved permanent.

Common questions

What was the Roman Empire?: The Roman Empire in its undivided phase ran from Augustus (Octavian), who became princeps in 27 BC after defeating Antony and Cleopatra at Actium (31 BC), to the death of Theodosius I in AD 395, after which the empire was permanently divided administratively between his sons. At its height under Trajan (AD 117) it stretched from Britain to Mesopotamia, ringing the Mediterranean (Mare Nostrum).
When is the Roman Empire shown on the map?: The border data draws the Roman Empire AD 1–394. The source samples borders at fixed dates, so a span can begin late or run on past the end.
How large was the Roman Empire?: At its greatest extent drawn on this map, the Roman Empire covered about 5.4 million km². That is the largest area the border data gives it across the years it is drawn, not necessarily its greatest extent in history.
How was the Roman Empire governed?: The Augustan settlement (the Principate) preserved republican forms — Senate, consuls, assemblies — while concentrating real power in the princeps, who held imperium proconsulare maius and tribunicia potestas.

Sources

This compendium cites its sources once for the whole document rather than per territory. Its bibliography names the English Wikipedia articles for each territory and its key figures as the primary basis, with Encyclopædia Britannica, the World History Encyclopedia, and academic and primary sources — Jordanes, Procopius, Gregory of Tours, Bede, Ammianus and the Anglo-Saxon Chronicle, read through the secondary literature. The article this entry is anchored on:

Wikipedia — Roman Empire en.wikipedia.org/wiki/Roman_Empire

This entry was last updated 27 September 2026.

This entry was researched and drafted with AI from the sources above, and has not been reviewed by a historian. How entries are made

Text available under CC BY-SA 4.0: reuse it with a credit to The World Through Time and a link to this page. Passages drawing on the Wikipedia articles listed above are also licensed CC BY-SA 4.0 by their contributors.

Border geometry for the map itself comes from Cliopatria v0.12 (Seshat Global History Databank, CC-BY-4.0).

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