How Long Can Rome Plausibly Hold Mesopotamia?

So I was thinking about this when I was trying to come up with the largest Roman Empire possible on paint (I was really bored), so I decided to ask you guys this. I know this question has come up a lot, but I thought it'd make for a nice discussion.

Assuming Hadrian doesn't willingly give up Trajan's conquest of Mesopotamia, or someone other than Hadrian succeeds Trajan, how long do you think the Romans could plausibly hold on to Mesopotamia before the Parthians or *insert Persian group here* retakes it? I would imagine 100 years would be possible but I am not too sure.
 
So I was thinking about this when I was trying to come up with the largest Roman Empire possible on paint (I was really bored), so I decided to ask you guys this. I know this question has come up a lot, but I thought it'd make for a nice discussion.

Assuming Hadrian doesn't willingly give up Trajan's conquest of Mesopotamia, or someone other than Hadrian succeeds Trajan, how long do you think the Romans could plausibly hold on to Mesopotamia before the Parthians or *insert Persian group here* retakes it? I would imagine 100 years would be possible but I am not too sure.

Depends on resistance level from the locals and if another group comes in that's more stronger then the legions. I think the longest it would have been held, baring accident, was the Third Century Crises. Then, it wouldn't have been stable enough to hold onto. Even though the East wasn't nearly as affected by it was the West was.

In my TL, I had it where they held the area until Islam arose and then they were unable to hold it, splitting the Empire in two.
 
I think the longest it would have been held, baring accident, was the Third Century Crises. Then, it wouldn't have been stable enough to hold onto. Even though the East wasn't nearly as affected by it was the West was.

I have to agree with that. In OTL, with the infighting and civil wars during the Crisis of the Third century, the Roman Empire was an alluring target and suffered attacks from the east anyway. With more territory in Mesopotamia for the Legions to defend (classic over extension), it would have fallen quickly (to Palmyrene?? or to the Parthians).
 
What effects would this have on the Parthians througout the century until the 3rd century crisis. Mesopotamia is vital to the Parthians as well. Maybe if Rome gets lucky. Parthia disintegrates and instead of one strong Sassanian like state replacing them, they fragment.
 
What effects would this have on the Parthians througout the century until the 3rd century crisis. Mesopotamia is vital to the Parthians as well. Maybe if Rome gets lucky. Parthia disintegrates and instead of one strong Sassanian like state replacing them, they fragment.

Basically it would collapse. It wouldn't be until perhaps Islam comes along before they'd really be unified in my mind. Either way, if the Parthians collapsed and no Sassaniads come along, Eastern Rome at least would have lasted quiet a bit longer than it did. Perhaps until the 16th Century.
 
I doubt Islam would come along.

Islam is entirely different than the Sassanids though. Muhammed could still have uited the Arabs and they could have risen to might. But, let's say they didn't. But Western Rome fell all the same. Who would have contested the Eastern Roman Empire? Crusaders? There would have been no reason for there to be crusades unless the Pope felt he needed to cleanse the heresy of the Eastern Orthodoxy. Maybe the Mongols?
 
Mongols, nonMuslim Turks, nonMuslim Arabs, Bulgars, Avars. . .

Finding enemies or potential enemies for the ERE is as easy as finding a list of the major groups of Eurasia west of India, and that's not counting something like the Mongols.
 
Mongols, nonMuslim Turks, nonMuslim Arabs, Bulgars, Avars. . .

Finding enemies or potential enemies for the ERE is as easy as finding a list of the major groups of Eurasia west of India, and that's not counting something like the Mongols.
All of which arrived in Rome's neighborhood long after the conquest and loss of Mesopotamia.
 
Mongols, nonMuslim Turks, nonMuslim Arabs, Bulgars, Avars. . .

Finding enemies or potential enemies for the ERE is as easy as finding a list of the major groups of Eurasia west of India, and that's not counting something like the Mongols.

However, would they have had enough manpower to really threaten the Empire? I mean, besides the occasional raids, without Islam banding many of them together, they would probably just be fighting amongst themselves much more then be concerned with fighting the Romans.
 
However, would they have had enough manpower to really threaten the Empire? I mean, besides the occasional raids, without Islam banding many of them together, they would probably just be fighting amongst themselves much more then be concerned with fighting the Romans.

You do know that not all of the Empire's were Muslim, correct?

And I don't think that Islam would necessarily be the only thing that could glue the ones that were Muslim OTL together.

Zuvarq: I know. I was responding to the issue of what the Eastern Roman Empire would be contested by - the list is longer than my arm.
 
You do know that not all of the Empire's were Muslim, correct?

Of course they weren't all.

However, Islam was a great binding force of those Arab peoples and gave them direction. I'm not sure all those people could have been brought together so effectively in any other way. Perhaps the barbarians from the west could have attacked their western borders and pushed through, but they were pretty content with what they got in the west it would seem.
 
Of course they weren't all.

However, Islam was a great binding force of those Arab peoples and gave them direction. I'm not sure all those people could have been brought together so effectively in any other way. Perhaps the barbarians from the west could have attacked their western borders and pushed through, but they were pretty content with what they got in the west it would seem.

Bulgars. Avars. Other western historical enemies.

So no "perhaps the barbarians from the west. . ." as if they weren't fighting enemies from the West OTL.
 
I think that Roman Mesopotamia falls into the "unlikely but doable" category. If the Romans do well, they can hold it for maybe 150 years or so, perhaps a bit less. This will probably butterfly the Third Century Crisis as we know it, and it's certain that Muhammad will never be born, so no "Islam" as we understand it will ever arise.
 
I think that Roman Mesopotamia falls into the "unlikely but doable" category. If the Romans do well, they can hold it for maybe 150 years or so, perhaps a bit less. This will probably butterfly the Third Century Crisis as we know it, and it's certain that Muhammad will never be born, so no "Islam" as we understand it will ever arise.

For that, you must get rid of Sassanids as a serious threat to Rome (or any major power from Persia). And you would need a strong Roman military presence in Mesopotamia to guard the far territories in the east for it to be secure enough that, when the time come, perhaps a certain Roman emperor (if not butterflied away) won't be forced to bribe tribes on the other end of the Empire and be killed for it.

I do think imperial over-extension does play a large role here.
 
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