Rome wasn't built in a day, according to an old adage. The Roman Empire grew over hundreds of years from a city state to a huge empire stretching from Britain to Egypt.

Rome and its empire were not destroyed in one single day. Rome was the center of the empire for a long time, but as the city's fortunes changed, the seat of power moved to the east and west. Why did the Roman Empire split into two? Is it possible that it happened quickly?

Other factors, such as political and social instability, revolts, invasions and incursions into the empire, led to the split.

Rome fell.

RECOMMENDED VIDEOS FOR YOU...

A vast empire

It's easy to think that the Roman Empire splintered because it became too big, but according to Mark, it's more complicated than that. Rival Roman rulers and foreign tribes were threats to the Roman Empire's borders.

The size of the empire was impressive.

Peter Heather, professor of medieval history at King's College London in England, said in an email that the Roman Empire was the biggest state western Eurasia had ever seen. It used to be possible to travel 20 miles a day over land, but now it's possible to travel 400 miles or more. The Empire was 20 times larger than it appears to us today due to the fact that it takes a person to cover ground.

Much of Europe, as well as parts of Africa and Asia, were conquered by the Roman Empire. From the Atlantic Ocean in the west to Iraq, Kuwait, Turkey and Syria in the east, it went.

The Romans were a victim of their own success. As it grew, it incorporated many different regions and cultures. Attacks by Goths and other barbarian groups became more common as a result of this.

The Roman Empire's split was not solely due to its size. The total explanation is not the size that was from the 1st c. Heather said that we only see a system split in the 4th century.

At its height, the Roman Empire's roads traversed continents to connect important cities and towns to its capital city.

At its height, the Roman Empire's roads traversed continents to connect important cities and towns to its capital city. (Image credit: Shutterstock)

What other things played a role? Two additional factors compounded the problem of distance. The rise of Persia to superpower status in the 3rd century A.D. meant that Rome had to have an emperor near the Persian frontier. The fourth century changed the definition of Roman to include provincial elites from Scotland to Iraq. The scale of the Empire made it unlikely that many "Romans" had any connection with Rome. It was thought that by splitting the empire it would be easier to oversee the different cultures.

Latin is a dead language.

Final split

Prior to the final East-West divide in the fourth century, the Roman Empire had been divided.

The split is often thought of at a certain point. When the Roman emperor Theodosius I died and was succeeded by his sons, they became rulers in the East and West.

All roads lead to Rome.

The principle of collegiate rulership had been part of the framework of imperial government for more than a century. The emperor of A.D. 284 was experimenting with various configurations of imperial government. There was a rule of four between two senior emperors and two junior emperors.

After the abdication of Diocletian, the empire fell apart, and after several battles for power, the empire came back together. The empire was divided again after Constantine's death.

Bust of Diocletian (Roman Emperor).

This is a bust of Roman Emperor Diocletian (Gaius Aurelius Valerius Diocletianus). (Image credit: INTERFOTO via Alamy Stock Photo)

If the year 395 was when the empire split in two, why do historians think it was? The division looks more stark in hindsight.

The idea that Theodosius I was the last ruler of a united Roman Empire is nonsense, according to the author. For instance, Theodosius "almost always ruled with someone else, even if he chose not to recognize some of those colleagues as legitimate emperors," which would indicate that a "split" was already in place before 395.

What was the relationship between the two states after the empire split? Is it possible that both sides of the empire worked together?

Heather said that it wasn't always the case. It was difficult to maintain good relations between coworkers over the long term. This was an unavoidable problem because it was done because it was necessary.

The two of them agreed with Heather's statement.

The ideal was for both parts to be in agreement. Military assistance was sent to the West from the East to fight the Vandals. There were some tense moments. Relations could break down.

It was often the case that the East and the West wouldn't accept the nominations of the other. During the time of Stilicho's ascendancy in the West, Eastern appointees to the consulship weren't recognised. The emperors in different parts of the empire had been at odds with one another.

Nero fiddled while Rome burned.

The consulship was seen as a reward rather than a high-powered job at this time. To shun a consul was to show disrespect to a hero.

A house divided…

In A.D. 476, the emperor Romulus Augustulus was overthrown and the Western Empire collapsed. The end point of the Western Roman Empire is believed to be here.

Heather doesn't think that the Eastern Roman Empire is part of the true Roman Empire.

Heather believes that the Byzantine Empire was a successor state to the Roman Empire.

It was originally published on Live Science