Why the Roman Empire did not expand any more?

Source: https://wondersofthepast.quora.com/Why-did-the-Roman-Empire-stop-expanding

I have found quite interesting those opinions on the reasons why the Roman Empire did not expand anymore that I have found in Quora. I have someway summarized the text.

David Fiore

This map represents the Roman Empire not at its maximum expansion, but at the death of Octavian Augustus in 14 AD.

The regions in yellow were those with a strong Roman influence or, in some cases, had been clients of Rome. The thing was that for Rome, the only thing truly useful to conquer was the Persian Empire.

Outside the Persian Empire (and with it, India, little known to the Romans, and China, almost unknown), there was nothing left to seriously conquer. There was nothing left that could bring profit to Rome, enough to justify a military campaign. Britain was taken in 43 by Claudius, Thrace was annexed peacefully, Armenia returned under Roman influence in 117, and the rest was barren land, forests, and cold.

The Persians were still a major power in the ancient world, and the Romans had many memories of many military defeats suffered because of them. It is worth remembering that in these battles, the Romans engaged only their Eastern legions, and therefore not even 1/10 of their entire military power, against the Parthians, who apparently did not hesitate to send all their armies to war to defend the Fertile Crescent.

So, simply put, Rome did not expand anymore because it no longer needed to on one hand, and on the other hand, it was no longer convenient.

Carl Richard Archie

My professor, put the answer this way, the Romans ran out of people to rob. This was Rome at its maximum extent:

This takes a massive army to maintain and that requires money. I will say something unpopular, after conquest, a standing army is a financial drain. Soldiers produced nothing but cost you a great deal and you must feed them locally.

Thus the conquests must:

• Be worth the value in permanent productivity and taxation
• Better hope you have a weak neighbor with low organization and social cohesion. Otherwise, you will have a lengthy oozing wound that exhausts your army and financially wrecks you with continuous war

So, to the South, Romans would be expanding into the Sahara; what was the point of that?

Expand into Northern Britain was done several times; those were financially unsustainable. North of the wall, population density was too low to sustain legions.

Along the Rhine, the Romans had expanded into Germany, on many occasions. It was a place of forests and swamps and small villages. Along the coast was one giant coastal wetland. No profit in that place, the Romans tried for years but it was just not profitable. This permanent fort was found in Thuringia, Eastern Germany:

Why was it abandoned? Finances.

Further along, was the Danube frontier. After Dacia’s gold was exhausted, it was not worth keeping it. Indeed, that frontier was open to the horse people and Germans. There was nothing to gain there. So, the Romans retreated to the Danube and stayed there.

To the east, was Persia or Parthia or whatever you want to call them. Those boys were as civilized, organized and militaristic as the Romans. From Crassus onwards, there was war, back and forth, back and forth, expansions, contractions, expansions, contractions…that war continued into the Byzantine era. Some claim, it never ended.

Conquest for conquest sake was not the point. Making profit was the point. Rome had run out of profitable places to conquer in their vicinity.