The Gallic Empire is the modern name for a breakaway realm that existed from 260 to 274. It originated during the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

's Crisis of the Third Century

Crisis of the Third Century

The Crisis of the Third Century was a period in which the Roman Empire nearly collapsed under the combined pressures of invasion, civil war, plague, and economic depression...

.

It was founded by Postumus

Postumus

Marcus Cassianius Latinius Postumus was a Roman emperor of Batavian origin. He usurped power from Gallienus in 260 and formed the so-called Gallic Empire...

 in 260 in the wake of barbarian

Barbarian

Barbarian and savage are terms used to refer to a person who is perceived to be uncivilized. The word is often used either in a general reference to a member of a nation or ethnos, typically a tribal society as seen by an urban civilization either viewed as inferior, or admired as a noble savage...

 invasions and instability in Rome

Rome

Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...

, and at its height included the territories of Germania

Germania

Germania was the Greek and Roman geographical term for the geographical regions inhabited by mainly by peoples considered to be Germani. It was most often used to refer especially to the east of the Rhine and north of the Danube...

, Gaul

Roman Gaul

Roman Gaul consisted of an area of provincial rule in the Roman Empire, in modern day France, Belgium, Luxembourg, and western Germany. Roman control of the area lasted for less than 500 years....

, Britannia

Roman Britain

Roman Britain was the part of the island of Great Britain controlled by the Roman Empire from AD 43 until ca. AD 410.The Romans referred to the imperial province as Britannia, which eventually comprised all of the island of Great Britain south of the fluid frontier with Caledonia...

, and Hispania

Hispania

Another theory holds that the name derives from Ezpanna, the Basque word for "border" or "edge", thus meaning the farthest area or place. Isidore of Sevilla considered Hispania derived from Hispalis....

. After Postumus' assassination in 268 it lost much of its territory, but continued under a number of emperors and usurpers.