Wow, lots of stuff here. Time for me to put on my jaded AH cynic hat and start blowing holes through it.
Fine with me if someone plays Devil's Advocate, but I'll fight it eagerly for the sake of victorious Romanitas. Nations suck, Empires rock. All Under Heaven.
When Augustus took over, there were exactly three more major campaigns - the (attempted) conquest of Germania, under Augustus' best friend, son-in-law, and heir; the conquest of southern Britain, under Claudius; and the conquests of Dacia and Mesopotamia, under Trajan.
In order to keep up the pace of conquest like this, you need an endless succession of strong, martial Emperors, in a strong, unified, and above all
loyal empire. Augustus and Claudius managed it because they hadn't quite burned through the new regime's stocks of political capital yet; Trajan managed it because he was reigning at the absolute, unarguable apex of Roman power and Imperial authority. Managing a major campaign on the scale of Germania every decade, more or less, is far beyond the ability of the Principate's structure to support. (Also: why have Tiberius conquering things but not Vespatian?
)
Ahh, but this additional expansion of the early Empire simply assumes that the major campaigns that it did undertake and you mention are more successful than they were OTL, something wholly plausible.
The right PoDs or butterflies (if we use a slightly earlier PoD like a surviving Caesar) make the conquest of western Germania as successful as the ones of Gallia and Britannia were OTL. The conquest of eastern Germania, Marcomannia, and Dacia would almost immediately follow after western Germania is pacified as the natural strategic completion of the former success.
Conquest of Britannia occurs on schedule a generation and half later, when the pacification of Germania and Dacia would be essentially done and military resources freed. The decision to annex Caledonia is relatively trivial to implement and may come as a plausible butterfly for various reasons, and it lays the ground to annex Hibernia as the natural extension of the previous conquest of whole Britannia. Same reasoning with Cimbria and Germania.
As it concerns Nubia, Rome did get a major victory that would have allowed its annexation under Augustus, here is it simply assumed that the Empire simply chooses not to give the Nubians a lenient status quo peace. If Nubia is annexed, the later conquest of Axum after a generation comes as its natural extension.
Since ITTL Dacia is annexed a century in advance, it is assumed that the OTL conquest if it under Trajan is substituted with a mix of various relatively minor "mopping up" conquests (Hibernia, Axum, Cimbria) to round up and reach natural borders.
And since the eastern border is much shorter and Germania-Dacia are already well underway to Romanization after three generations, and Britannia is already pacified, Trajan's empire has plenty of resources to stabilize the Zagros border and keep Armenia and Mesopotamia for good (and quite possibly make rump Iranian Parthia a client state).
As you can see, this set of conquests does not assume that the early empire has to make any really extra major conquest effort, only that the ones they did are optimized.
The fine details about the apportionement of conquests between the various Emperors is wholly tentative and subject to butterflies, so something might well be conquered under Vespasian and not under a different emperor. See above for what I regard as the rough overall pace of conquest.
More to the point, Marcus Aurelius' wars were entirely defensive; conquering Persia (apart from being way to big for the Empire to digest) was never remotely on the cards. Ditto Sarmatia, which has the additional problem of being beyond the "able to support a legion" line (this is also why, despite drubbing the Picts every decade for two centuries, nobody from Claudius to Septimus Severus bothered to put a garrison in Scotland).
OK, this is entirely reasonable, but conquering Persia and western Sarmatia is only an optional part of the scenario. However, TTL's Marcus Aurelius would wage his wars with the advantage of much more favourable borders on the Vistula-Dniester and Zagros, fully Romanized Germania, Dacia, and Britannia, and fully pacified Mesopotamia. It is entirely feasible that because of this, he may deem that the Empire can afford to turn his victories into some extra conquests. Of course, it is also entirely possible that he still enforces the status quo as IOTL, and whether annexing Parthia and western Sarmatia would be a net benefit or burden to the empire is open to discussion.
Besides, garrisons on the Dvina and Dniepr could be easily supplied by river, those trade routes saw major traffic during the early Middle Ages, and by the time they would annex western Sarmatia, Germania and Dacia would be already fairly well developed. And what's this nonsense about Caledonia ? Rome can supply it by sea, crossing the Channel and coasting Britannia, quite nicely.
Caesar was going to go for Parthia immediately after his assassination, but again, Parthia's a big chunk to digest, and even clientizing it would be a big task too. God knows what Caesar's goals were - boundless ambition and all - but the most likely result was probably just the avenging of Carrhae and a slightly better border in upper Mesopotamia.
Given Caesar's mindset and capabilities, and the extent of his OTL conquests, I think he would settle for nothing less than the annexation of Mesopotamia and Germania at the very least, and it would be well within his ability. He would likely harbor further ambitions about Persia, but it is quite possible that he would settle for making Persia a client, like he did with Egypt, and he may or may not succeed at it. Conquering Persia itself is much less feasible, at this stage.
Even taking all of Mesopotamia would be tough, and require a lot of work to maintian (Mesopotamia has essentially 0 natural defences V the Iranian plateau, and the Parthians are going to take a stab at reconquering it every generation for about forever). Hadrian retreated to the old line in the Levant for a reason.
The Vistula-Carpathian-Dniester border would free up a lot of legions, Mesopotamia was the richest province of Parthia, a Persian state without it would be greately weakened, the Zagros outskirts make for an excellent natural border that Roman engineering could bulk nicely with a limes.
Annexing Mesopotamia gives a very rich and popolous province to the Empire, deprives Persia of it, and creates a border which is rather more defensible than the longer Euprathes-Syria border, a desert plain.
It seems likely the heavy plough / horse collar would show up after the Roman conquest, but not particularly significant - getting it at all would be a huge help to stabilizing things, yes.
It is wholly reasonable to assume that the ownership of all that extra fallow land could spur the quick development of agricultural technology to exploit it in full. After all, the heavy plough and horse collar were fairly quickly developed IOTL, after Northern Europe was integrated in agricultural economy, in conditions much less optimal for steady technological progress than Rome at its heyday.
Its problems were always structural. The number one problem: the generals you talk about. As I mentioned above, the generals were a huge problem without them going off and gaining military glory, and Rome ITTL is going to have huge problems with its generals coming back to haunt it. The Third Century Crisis might be the good thing to look at here - the Empire, from a starting position of great strength and essentially no outside threats whatsoever, essentially got dragged to its knees, solely by internal strife.
This is entirely true, but there is more to it: the extra resources the Empire gains by owning Romanized Germania, Mesopotamia, Nubia, and Arabia Felix, the denial of same resources to barbarians and Persians, more defensible borders which make for a more indepth protection of the Empire's core, all those factors may easily mean that the Third and Fifth Century Crises are substantially diminished in their long-term consequences, they are no more the start of a death spiral, but a temporary crisis which Rome fully recovers from in due time, much like the Second Punic War or China's various dynastic crisis, or at the very most they may trigger the permanent division in WRE and ERE and nothing more. TTL turns Germanics and Arabs into extra resources from a big problem, and nerfs Persian empires. This is far, far from trivial about late antiquity crisis becoming a death spiral or not.
The China analogy seems a bit strained - China was one, giant, homogenous mass through the entire last 2 millennia of its history. The thing was unsinkable.
Chinese civilization did not magically sprung fully formed into its late imperial borders at its birth. Its expansion was a millennia-long steady work of expansion, colonization and assimilation from its cradle alongside the Yellow River.
Rome was heterogenous from the get-go
Give Rome some extra time and success, remove the Migrations, and the cultural imprint of Rome on Europe would become as indestructible as China had on its own mainland. The very existence and spread of Romance languages, and the huge grip the ideal of Rome had on later Europe, are proof to it.
I concede that the main long-term difference between Rome and China would be the deep-rooted dualism between Latin and Greek areas which is likely to last. But at the very most this can pave the way to recurrent or permanent division between West and East (China has always harbored a similar north-south economic/political dualism that never went to permanent division). Give Rome some extra optimal headstart, Latin-Greek culture would eventually and totally affirm in Romasphere, and the ideal of imperial unity would become as unshakable in its ruling and middle classes as it was in China.
and just didn't have the time China did to assimilate things - the civilized East turned back into Greeks within a century of the break-up and the Roman civifiying mission never really caught on in the west. If the years 40 - 450 disappeared in British archaeology, you'd be essentially unable to tell where the gap was.
Again, a more successful Empire could well evolve into a WRE/ERE division, because of underlying dualism, but this is far, far different from the OTL fragmentation. Romanization of the West was well underway (see Romance languages) and it was only reversed because the West was carved up into tribal kingdoms by Germanic migrations. ITTL those Germanic peoples would be as Romanized as the inhabitants of Gallia and Iberia, residual unassimilated barbarian tribes from Scandinavia and Sarmatia and the steppe nomads simply would not have the manpower to implement the cultural and political substitution of Roman Europe that Germanics did OTL, even assuming the Huns stage a successful conquest of Rome or the WRE/ERE (a very questionable assumption with this Empire), at the very most it would be a temporary dynastic takeover that would not harm the lasting cultural and political integrity of the Romasphere.
Your statement about the archeology of Roman Britannia is hilarious, and anyway ITTL Saxons would be as Romans as the Britons themselves.
About Roman steam engine, I fully agree that the Empire did lack the technological basis to make it work in its OTL span, but this is not nowhere necessary to its survival. An empire that makes a lasting recovery from its late antiquity crisis shall butterfly away the Dark Ages, and steadily proceed to the technological advances of OTL Islamic Golden Age and European High Middle Ages, either by autonomus development or exchange with China. That's more than enough to remove most of the technological weak points that the Empire had.
No Dark Ages, true, but Rome wasn't exactly great on progress - it stultified pretty badly after about 100 CE or so.
A clichè with very little basis in fact. The fact is that political and economic collapse of the late empire was not exactly optimal for progress.
I've never heard of 10th C ships being able to make it to the New World (unless you mean longships, and even then they skirted Iceland and Greenland),
Ever heard of Vinland ? When Rome discovers America, either by itself, or riding on the coattails of Norse explorers, it shall be by following the Iceland-Greenland-North America route, I agree that a replication of the Columbus voyage is terribly unlikely.
and more to the point, why would the Romans? They don't have a bunch of angry Arabs and Turks between them and China,
True, at the most they have Persia as a block, assuming they don't assimilate it or make it a client. Moreover, since they fully control the Red Sea route all the way to Yemen and Ethiopia, they have the incentive to maintain and improve the Suez canal, develop a decent ocean-going technology, and go by the India-Indonesia route.
However, once they do develop a decent ocean-going technology, they are bound to start major-scale exploring. Mastering the Indian ocean route to China and to a lesser degree circumnavigation of Africa shall be their top prorities, but since they hold the British Isles, sooner or later they are going to explore the Iceland-Greenland-Vinland route as well. The huge agricultural potential of North America cannot escape the notice of Roman explorers, and Native Americans are a trivial concern for Renaissance Roman settlers and legions.
However, I easily concede that if Rome is strong and technologically advanced enough to undertake a major exploration and colonization of the Americas, its first priority shall be colonization and assimilation of Sarmatia, Persia, and Central Asia, exploration/trade with India, Indonesia, and China, and quite possibly they can eventually envisage conquest of India, esp. if Persia was assimilated long ago, but it is also possible they are happy with making India a client.
If the survival and expansion of Rome butterflies Indian unity into existence, it may or may not have the resources to withstand Roman penetration. A disunited India is rather unlikely to withstand Roman colonization, even if it is only done by a WRE or ERE, if it stays independent it is most likely because competition with other roman half or China stalemates expansion.
Persia proper or a united Rus (say Rome's survival deflects Norse expansion almost entirely into Sarmatia, and they create a sturdier Rus than OTL) have far less chances, they absolutely would not have the resources to withstand expansion by a united Rome with Exploration Age technology. A Renaissance WRE would very very likely swallow a united Rus but it is not a given, a disunited Rus has no chance. Ditto for Persia and Renaissance ERE.
Norse colonies in the Americas are quite possible, a Norse America is feasible but only if Rome is too busy expanding in the East to bother about the New World for several centuries.
and unlike that rassum frassum Columbus, they know how big the world is and how impossible getting to China would be.
Very true.
Again, I doubt it - if anything it will make the 3rd century crisis worse since reestablishing central authority all across the empire will be harder.
Not necessarily. This empire has the vast majority of its legions concentrated on two relatively short borders in comparison to OTL, Vistula-Dniester and Zagros. It is quite likely that during dynastic crises, the Sarmatian and Persian legions are going to come up with one pretedent each relatively quickly, either by agreement or battle. Besides that, one extra pretendent may arise in Rome from the Senate or the Pretorians (if these bodies disgree, one victorious pretendent shall arise among them very quickly for obvious reasons).
It means that at the worst, dynastic crises shall see 2-3 pretendents, civil wars shall be intense but quickly settled and the recurring tendence of the empire shall be to split into western and eastern halves. This all indicates that civil wars are going to be no more destructive than OTL and shall bring west-east dualism into fore, even more so than OTL.
A lasting dynastic cycle of west-east dualism, much like the Chinese north-south one, is the most likely natural outcome. Because Rome dualism was fueled by a cultural divide that China lacked, at some point this division may or may not become permanent, but that's the only major difference.
I doubt it could conquer either, it certainly couldn't assimilate either, and in general the conquests would be a massive drain on the Empire, for the reasons mentioned above.
I agree that is questionable whether Rome would keep Persia or Sarmatia after a major victory on either front, but conquering either looks quite feasible if the other border is quiet.
Certainly lasting conquest or vassallization of Persia seems within this Empire's grasp. I agree that a complete cutural assimilation of Persia is not that more likely than a solution to Latin/Greek dualism, but neither is Persia remaining more unaffected by long-term Roman domination than OTL Arab domination.
A vassal or annexed Persia would turn the Latin-Greek dualism into a three-way Latin-Greek-Persian divide. However the limited dimensions and resources of Persia in comparison to the WRE and ERE would not make it any substiantially worse than the original dualism, and most likely this could pave the way to the permanent breakup of Persia (again, until the roman successor empires master Renaissance technology, then it0s a wholly new game).
Western Sarmatia was a largely empty place with a scattering of Finnish, Germanic, Slavic, and Iranian tribes. As you indeed pointed out, like Persia, defending the place would add significant logistical burdens to the Empire, but militarily the conquest itself would not be that much difficult.
Just like Germania, if Rome does hold the place for long, it can be gradually developed by a mix of Roman colonization and native settlement, until it becomes something much like the Middle Age equivalent, at such a point it would become a net asset and not a burden to the Empire, or at least significantly contribute to paying for its own defense.
I agree that demographic, economic, and logistical conditions (if the heavy plough and horse collar are available) are such that Rome would develop Germania much quicker than Sarmatia. By the time that the crisis of late Antiquity shows up, Germania would be essentially indistinguishable from the rest of Roman Europe, while Sarmatia would be at best an half-way patchwork. But the same model could be successfully applied.
Except the *Sassanids will rise up anyways, in all likelihood, just against the Romans rather than the Parthians;
And a strong Rome could crush their uprising in an annexed or client Persia just like it did so for many other nationalist revolts. Ask the Jew Zealots.
The *Sassanids only have a good chance if their rise is timed with a Roman dynstic crisis, and even so, it is questionable whether they can withstand the offensive comeback from a recovered Rome.
and trading the Euphrates (close to the Mediterranean, defensible) for something out in the 'stans (just look at it) will do bad things for Rome's strategic situation out east.
Very true. OTOH, the Zagros are a much more defensible border than the Euphrates, they weaken Persian Empires a lot. The advantages of conquering or vassallizing Persia are twofold: it removes the last developed rival on Rome's borders, and it gives Rome full control on trade routes to India and China. They are far from trivial, and need to be weighted against the more extended borders on the east, as the respective benefits and drawbacks of annexing or vassallizing Persia.
Again, the longer, further-away, less locally supportable border would be much worse, IMHO.
True but in the long term, conquered Sarmatia shall be colonized and developed to Middle Age levels, and the lack of local support shall no longer be an issue.
Neither is best, and I suspect the Empire (at least, those borders) will not last out the Huns anyways.
Neither the Huns nor the Sarmatian tribes in the 4th-5th century have nowhere near the population basis necessary to carve up major bits of the Empire into lasting tribal states, even if they manage to stage a strategic breakout of the Sarmatian limes, which is only likely to succeed if Rome is in the grips of a dynastic crisis. At worst, whatever they grasp shall be almost surely reconquered by Rome in the dynastic collapse the Hun empire suffers after *Attila's death. Without the Germanic Migrations, the Huns don't have the population bulk to make lasting damage to the Romasphere, like they did not to the Chinasphere.
I'd say OTL + Germany + Mesopotamia and maybe a few bits and pieces (Dacia, Nubia, Arabia Felix) is the most that could be plausible, and even then it'd be a strain.
No strain whatever, since those gains provide better borders and extra resources to Rome, and deny them to its enemies.
Scandinavia is utterly impossible - no imaginable way of supporting garrisons, let alone Roman colonies.
And the problem with supporting garrisons and colonies in southern Sweden with naval shipping from Britannia, northern Gallia, Cimbria, and Germania would be ???
It is true that if it happens at all, Rome would undertake the conquest of Scandinavia only if and when western Sarmatia is conquered and fairly settled, and the Huns are repelled, so substantially beyond late Antiquity timespan. Quite likely, if it happens at all, it is as a military reaction to Norse expansion. By the time Rome seriously plans about expanding into Scandinavia, western-central Europe shall be as Roman as Italy.
Western Sarmatia is a stretch at best, Eastern Sarmatia is incredibly laughable.
Just like Scandinavia, eastern Sarmatia could and would be conquered only if and when western Sarmatia is conquered and fairly developed, so that it can support further expansion. It would happen well beyond the span of late antiquity.
OTL + Germania, Dacia, Nubia, Mesopotamia, Arabia Felix may be easily done by the 1st century empire with the right PoDs and butterflies, but not much more than that. Shaky conquest or vassallization of Persia in early or late 2nd century may or may not happen, just like shaky conquest of western Sarmatia in late 2nd century. Temporary vassallization of Persia in 1st Century only if Caesar is around to pull it with one of his military miracles, and then again a mess to maintain until Germania and Britannia are basically done.
A century of overall defensive consolidation and two centuries of development would make western-central Europe basically Romanized, four centuries of development would make it fully so. Its development creates the basic demographic and economic groundwork Rome would need to entrench assimilation of western Sarmatia and/or Persia in earnest.
Depending on butterflies, the crises of the 3th and 5th centuries may or may not hit the Empire with varying severity (some components, like the Huns and plagues, are much less liable to TTL's butterflies) but in all likelihood the
lasting damage to TTL Empire is substantially lessened (the Empire has more resources and opportunistic external enemies have less).
Depending on their severity, the timeframe varies for the Empire to undertake the assimilation of Persia and/or western Sarmatia with really good chances of success, but at worst it would show up in the 4th or 6th century. If such expansion is done, the Empire is going to need another centuries-long cycle of development and consolidation before it can expand any further. For various reasons western Sarmatia and Persia are rather more complex to assimilate than previous conquests, so any further expansion is utterly unlikely before the start of the Norse Age and technological development to High-Late Middle Age levels or so.
Unless they take Persia (as already mentioned, unlikely and temporary at best) it won't make the slightest difference. They're too far away.
True, but see above about Persia. Even making Persia a client would make a substantial difference, and if they forsake or delay Sarmatian expansion, annexing and holding Persia proper is not that much difficult without the Germanic headache, if the bulk of Roman might is focused on it, Alexander and the early Caliphs conquered Persia fairly easy and their successors kept it for centuries, militarly and technologically they were no way superior to the Romans, and this Roman Empire fully controls the Red Sea, so it can supply garrisons in Persia by circumnavigation of the Arabian peninsula too.
Persia proper is not so vast nor populated than suppressing separatist revolts would be an headache task for a strong Rome (although I concede that Persia would tend to break away in any serious dynastic crisis). The main drawback of conquering (or vassallizing) Persia is that it give a rather worse border to defend against Central Asian nomads than the Zagros (even if the nomads would be a much less serious enemy than an hostile Persia). Anyway, even if Rome does conquer or vassallize Persia, its long-term control would perforce be limited to the Iranian plateau itself, any attempt to expand in the AfPak area would be a foolish venture, an embarassing failure, and quickly be abandoned.
Roman Polytheism was never a religion even to the degree Hinduism is;
Original Roman religion without Hellenistic polytheism was very ritualistic and spiritually dreary, pretty much an expression of cultural-political allegiance like Confucianism, and nothing as fulfilling as Hinduism, indeed.
However, a late synthesis of syncretic Greco-Celtic-Germanic polytheism with Roman philosophical schools and/or borrowings from Hinduism has the potential to evolve into something like Hinduism, Taoism, or Buddhism (i.e. both spiritually rich and philosophically sophisticated enough to provide for pretty much all the psychological needs of the average citizen, educated or not).
By the way, I have very serious difficulties to see how Hinduism would be any less fully a religion than monotheisms.
If collapse of the Roman Empire is not around to fan monotheism into a mass refuge for the majority of its urban population, paganism has a good chance to evolve this way. Ask Julian the Apostate and let's give the man the break and the £$%& like Ambrose, Tertullian, and Cyril the kick in the teeth they deserved in some TLs.
monotheistic religions (Christianity, but also Mithraism and others) took off for a reason
Yup, the collapse of the late Roman Empire.
(and during a period when the Empire was quite successful, too).
They started to fill a partially empty niche, so they spread somewhat, but only to a minority, as long as the Empire was successful and zero-sum competition with pagan mystery religions did limit their spread. Only the impending collapse of the Empire did one monotheism the critical boost. If that does not happen, it is quite likely that Christianity and Mithraism remain two minority cults among many in the fragmented religious market of the empire, which gives paganism a good chance to reform and fill the niche, and at that point it would have a substantial advantage from being much less antagonistic to Roman culture than monotheisms.
Judaism is almost certainly not going away, for the obvious reason of bloody-minded tenacity,
Very true, but it is not going to expand anywhere, either. It lasts, but it remains a fringe oddity in the cultural landscape of the Romasphere.
Zoroastrianism is never going to be under Roman rule long enough to disappear
See my argument above, a lasting Roman assimilation of Persia proper is far from unlikely in the long picture.
not to mention, Roman tolerance means nothing will happen to it barring a 60s Judean-type revolt
Very true, but the first time it is used as a separatist rallying banner this way, which is likely to some point, the Romans shall turn hostile to it, and if the Empire does not collapse, or Persia manages to break away for good (only really likely if the WRE/ERE split does so too), eventually stamp it out, especially if by the time, they have developed their own "imperial" religion. Even if they do not, however, they wiped out druidism.
, which in Persia would be likely to succeed.
Unless the Empire is facing the Huns on the other border, or is in the grip of a major dynastic crisis or temporary split, Persian revolts shall fare no better than Judean ones. The Sarmatian border is only going to be a major concern for a strong Empire when major tribal concentrations of steppe nomads show up, which they can only do every few centuries. The bulk of the Empire's military might can be easily refocused to suppress Persian revolts, there is not much else legions can be used besides guarding the Sramtian borders (and fighting civil wars), the Iranian plateau is not that much remote nor large nor populated.
Civil wars give such a revolt a chance to succeed, but what is lost during a dynastic crisis can always be reconquered when the Empire recovers, only if the WRE and ERE split permanently Persia gets a really good chance to split off for good as well.
Even assuming no real barbarians come knocking,
Which ones ? Germanics from Central Europe (and later Arabs) were the vast majority of them OTL. Here, they are loyal Roman citizens and bulk up the legions. Residual unassimilated Germanics and Slavs in Scandinavia and Sarmatia are a rather pitiful smattering in the timespan of late antiquity when barbarian migrations could build on dynastic crisis and steppe-nomad recurring expansion and make OTL lasting damage. They don't have the manpower. When they shall have built it up and steppe nomads shall show up again in 8th-9th century, the Empire (or its WRE/ERE successors) shall be so much demographically, economically, and culturally developed and integrated to make itself as invulnerable to lasting breakup as China.
this Empire will eventually fall apart into more-or-less warlord states - probably about the size of OTL's successor kingdomes -
Sorry, this is an entirely arbitrary and unimaginative copy and paste of OTL on a TL with wholly different foundations.
OTL tribal kingdoms and later nation-states only could arise because the invading Germanic tribes put them into shape. Here, barbarians are far too few to implement that kind of lasting change.
Both OTL patterns of splintering in the Roman Empire before the Migrations and the structure of TTL Empire indicate that during dynastic crises the Empire tends to divide into western and eastern halves, or at the very worst a Western-Central European "Carolingian" third, a "Byzantine" Greek-Middle Eastern third, the Italian-and-Mediterranean-stuff third that is too fragile and composite for lasting separation, plus the optional Persian shard.
Worse fragmentation does not tend to manifest without major barbarian settlement, and the more the Empire lasts, the more unlikely it becomes, since the cultural and economic pulls to unity become stronger and the demographic base of the Empire grows, making barbarian inroads pitiful in comparison and easily repelled or assimilated.
Sorry, without all those unassimilated Germanic tribes teeming beyond the Rhine and Danube, the nation-state fragmentation of Europe is doomed to stillbirth, oh joy.
And then the Central Asians will come a-knocking.
And they shall fare no better than with China. The legions kick their butts most of the time, every few centuries dynastic crises give them the window to set up a dynasty of their own, but that's all. The smattering of steppe nomad conquerors is culturally and demographically swallowed in the Roman sea. Eventually, Rome (or its WRE/ERE successors) pull themselves together, overthrow the foreign rulers, and endure.
