An old adage says that Rome wasn’t built in a day, which means big projects take time. The Roman Empirefor example, gradually established itself and grew over hundreds of years from a city-state to a colossal empire stretching from Britain to Egypt.

And just as Rome and her empire were not built in a day, neither were they destroyed in a day. For centuries, Rome was the center of the empire, but as Rome’s fortunes changed, the seat of power eventually moved away from the city and the empire finally split into two separate states in AD 395 – one in the east and one in the east. West. But why was the Roman Empire divided into the Western Roman Empire and the Eastern Roman Empire? And it happened quickly?

In short, the vast size of the empire played a part – its colossal borders made it difficult to govern – but other factors, such as political and social instability, revolts, invasions and incursions into the empire, also led to the split.

Related: Why did Rome fall?

A vast empire

It’s easy to think the Roman Empire fractured because it grew too big, but according to Mark Humphries, professor of classics at Swansea University in Wales, “it’s more complicated than that”. Besides its size, the Roman Empire also faced multi-faceted problems, such as rival Roman rulers and foreign tribes and empires threatening their borders.

Nevertheless, the size of the empire was impressive and created many challenges.

“The Roman Empire was the largest state Western Eurasia had ever seen, and while it looks large on the map, it was even larger in practice due to communication speeds,” said Peter Heather, professor of medieval history at King’s College London in England. Live Science said in an email. “On land, it was possible to travel about 20 miles [32 kilometers] a day, whereas now we can go maybe 400 [miles, or 640 km]. Since the true measure of distance is the time it takes a person to cover the terrain, the Empire was, for all intents and purposes, 20 times larger than it seems to us today.”

At its height, the Roman Empire covered much of Europe, as well as parts of Africa and Asia. It stretched from the Atlantic Ocean in the west to what is now part of Iraq, Kuwait, Turkey and Syria in the east.

The Roman Empire was, to some extent, a victim of its own success. It grew so vast that it incorporated many different regions and cultures, and as it grew, so did its borders. As a result, attacks and unwanted border crossings — mainly by Goths and other barbarian groups – have become more common and more difficult to combat in an effective and timely manner.

But Heather agreed that its size was not the only factor in the splitting of the Roman Empire. “Size isn’t the total explanation, because it was so large from the 1st century CE, and we don’t see a systemic split until the 4th century,” Heather said.

So what else played a role? “In my view, two additional factors compounded the fundamental problem of distance. The first is Persia’s rise to superpower status in the 3rd century. [A.D.]which meant that Rome had to have an emperor somewhere near the Persian border,” Heather said. The second is that by the fourth century, the definition of “Roman” had changed to encompass provincial elites from Scotland to Iraq. Many “Romans”, given the scale of the Empire, had little or no affiliation with the city of Rome itself: the splitting of the empire, it was thought, would facilitate the framing of these regions. and diverse cultures, very often different.

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Final distribution

The split in the Roman Empire was slow to come, and divisions had occurred before the final and permanent East-West divide in the 4th century, according to Humphries.

“We often think of [the split] occurring at some point. The date most commonly given is [A.D.] 395, when [Roman emperor] Theodosius I died and was succeeded by his sons Arcadius and Honorius, who became rulers in the East and West respectively,” Humphries said.

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“However, the principle of collegiality [having more than one emperor] had been part of the Imperial government framework for over a century at that time. Diocletian, who became emperor in [A.D.] 284, experimented with various configurations of imperial government.” Diocletian established a tetrarchy, or rule of four, between two senior emperors, or augusti – one in the east and one in the west – and two junior rulers, or caesars.

The tetrarchy collapsed shortly after Diocletian’s abdication in AD 305. three of his sons.

So if the Roman Empire was split long before the oft-cited date of 395, why do historians identify this year as the time the empire split in two? “I suspect what happens after 395 is that the division seems more austere in hindsight,” Humphries said.

There was perhaps an “over-emphasis on the unity of the Empire before 395,” Humphries said, adding that “the idea that Theodosius I was the last ruler of a united Roman Empire is nonsense. complete”. For example, Theodosius “nearly always ruled jointly with someone else, even if he chose not always to recognize some of these colleagues as legitimate emperors”, which would indicate that before 395 a “split was actually already in place, Humphries said.

So, once the empire split in two, how were relations between the two states? Did the two sides of the empire work closely together and function as a unified body?

“Not always,” Heather said. “It was very difficult to divide the office and maintain good relations between colleagues in the long term. It was done because it was necessary, but it usually generated tension, and it was an unavoidable problem.”

Humphries agreed with Heather’s assertion.

“The ideal was for two parties to reign in harmony,” Humphries said. “Emperors of the East and West issued coins in each other’s name, and military assistance was sent to the West from the East against the vandals. That said, there were moments of tension. Occasionally, relationships can break down,” Humphries said.

“For example, it often happened that the East and the West refused to recognize consuls named in each other. During the period of Stilicho [a powerful and  influential Gothic military leader] ascendant in the West, Oriental people appointed to the consulship were not recognized in the West in [A.D.] 399 and 400,” Humphries noted. “This refusal to recognize consuls had been a feature of earlier severances in relations between emperors in different parts of the empire.”

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At that time, the consulship was, according to Humphries, “an entirely ceremonial post” and was generally seen as a reward rather than a high-level job. To flee from a consul was therefore to show disdain towards an esteemed, often heroic, individual.

A divided house…

The Western Empire finally collapsed in AD 476, when Odoacer – a Germanic leader often called The first “barbarian king” of Italy (opens in a new tab) — revolted and overthrew the Emperor Romulus Augustulus. This is widely considered the end point of the Western Roman Empire.

The Eastern Roman Empire, also known as Byzantine Empiresurvived until 1453, although many historians – Heather included – do not consider it to be part of the “real” Roman Empire.

“I would say – and I’m not alone in this – that the Byzantine Empire was as much a successor state to the Roman Empire as any of its Western counterparts, such as the Visigothic or Frankish kingdoms,” said said Heather.

Originally posted on Live Science.