Roman Empire vs Caliphate

what if the whole roman empire survived the barbarian invasions and battle against the caliphate what do you think is the consequence of this....
 
I think that a surviving Rome would butterfly Islam away. But if the Caliphate or something like it fought Rome, the Romans would fight tooth and nail to hold Egypt and North Africa. Without those, Rome starves. Islamic expansion relied on internal weaknesses among the conquered people, so I assume Islam won't spread very easily much past Carthage, and maybe not very easily into Asia Minor. That assumes Islam expands at a rate similar to OTL. If a unified Rome is much more effective than the barbarian kingdoms, you might have Islam left in Arabia, Mesopotamia, and Persia.
 
Ditto on the butterfly. However, it was (more or less) the strongest part of the Roman Empire that did fight the Kalifaet - the whole reason that the Arab invasions fared so well OTL was the war exhaustion that set in in both Rome and Persia after centuries of war, which likely wouldn't change, even if the whole Empire survived.
 
A Roman Empire united, rather than being the seperate East and West empires would probably mean there wouldn't have been much of a Caliphate to start with.

Split into East and West, it may have been pretty similar to OTL, just with a united Europe etc. Maybe the western empire attacks the Caliphate?
 
It depends on if the Empire is split or if it's still one, I can see some western Emperor just letting the East deal with it, like with Persia, or just being to hard pressed on its own borders to send much help.
 
It depends on if the Empire is split or if it's still one, I can see some western Emperor just letting the East deal with it, like with Persia, or just being to hard pressed on its own borders to send much help.

what about the moorish invasion of spain?
 
Never mind spain, North Africa was the site of much of the grain production that fed Rome.
Not to mention that everything from west of Carthage is part of the Western Empire anyway. If some hypothetical alt-Islam began seriously threatening East Rome's hold on Egypt then the West would send help; the Western Emperor can look at a map and see that if Egypt falls then his lands would be under attack next.
 
I don't think it makes much difference.

The history leading up is that Justinian was bent on reconquering much of the Western Roman Empire. And he did pretty good, nailing down Yugoslavia, Italy, Spain and north Africa.

However, the Persians were a constant threat. So Justinian, as did previous Roman and Byzantine rulers, bought the peace with gifts. Basically: They paid tribute.

The Romans and Persians had been traditional enemies all over the middle east. At times, the Romans had pushed as far Mespotamia, but the Persians had pushed them back out. There were no real natural borders of demarcation, so Assyria and Palestine were simply notional places.

Anyway, Justinian's successors, as I recall, just decided to stop paying tribute. All those conquests were expensive, costs had to be cut somewhere.

The Persians invaded, sweeping the Arabian peninsula, driving into Syria and Palestine, taking Egypt and even pushing into Anatolia. Eventually, the Byzantines pushed them back out, and something resembling a status quo was restored.

But the trouble was, neither could really overcome the other decisively. Instead, they had bankrupted their treasuries, wrecked their armies and done considerable damage to their subject peoples.

It was in this state of complete exhaustion of the superpowers that Islam took place.

Mohammed united the Arab peoples of the Arabian peninsula for the first time. These included everything from settled and civilized traders and urbanites in Yemen, Mecca and Medina, to barbarian tribesmen in the hinterlands.

They came boiling out, and neither the Byzantines nor the Persians had the strength to stop them. In short order, Assyria, Palestine and then Egypt and Libya fell. Mesopotamia and Persia collapsed. The Byzantines barely threw them back from Anatolia.

If we assume that the whole Roman Empire was still around, I don't think it makes much of a difference. Had the whole of the Roman Empire went up against the Persians, I think the ultimate outcome remains. The Romans could not take the Persians down. At most, the Romans might have been able to prevent the wave of Persian conquests. But the end result would be the same, bankrupt treasuries and exhausted armies.

The Romans had no way to control the Islamic movement. At best, they would have seen it diverted into Mesopotamia and Persia. But then, the new Caliphate turns around and attacks with Arabia, Mesopotamia and Persia. The Romans could barely handle Persia alone.

There's no geographical barriers protecting Assyria or Palestine, and Egypt is sitting there like a plum. Sooner or later these would have fallen, and likely more sooner than later.

After that? Maybe Carthage and Algeria would have held out. That's iffy. Most likely, the Romans would have stopped the Caliphate at Morocco, no Spanish adventure. No conquest of Sicily. But that's it.
 
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