I was referring to the terrain, how due to erosion the famous choke point had widened to the point where it have required tens of thousands of men to properly defend it. I apologize for not being clearer.
Fair enough. Too bad we don't have many Iranian members on the board who could clarify exactly how narrow or wide the passes are.
Thanks for debunking your own argument?
No,you simply just have no idea about how northern China’s defended.A large part of what the Great Wall covers is inhospitable terrain,like mountains,deserts.In these parts,the area’s so inhospitable that apart from some raids,the enemy simply could not conduct any large scale assault through these areas.To conduct a large invasion however,the enemy will have to assault key locations like mountain passes that are definitely well defended.Most of the time,such attacks are repelled.In actuality,a number of dynasties like the Tang Dynasty didn’t even bother with the wall and simply just posted strong field armies that prefers to attack the enemy rather than be attacked.Whenever there is a problem,you don’t see armies from another part of the wall reinforcing a besieged section,rather you just get army units from other parts of the country further south marching to reinforce that area.The fact that the wall’s situated in an area not known to produce grain does not mean that the government could not support these troops.Grain from as far as south China was transported there.The Zagros is just next to one of the most productive agricultural fields on the planet.If the Chinese government can transport grain from Southern China on a timely manner to the north,the Romans can definitely transport grain from Mesopotamia to the Zagros.As you have mentioned,the two points are trade routes.This means they are well connected to Mesopotamia and beyond.
the actual frequency of Roman-Persian wars OTL makes me severely doubt that.
You keep making the same argument (that logistics can just be routed through Mesopotamia) then failing to understand that's an argument in favour of just moving the border back to Mesopotamia and cutting out a few days of marching and a few years of building roads through the foothills of a major mountain range.
I didn’t make the same argument.I went further and tore apart your claims of why making the Tigris River the border is feasible.
Have you read the first page of this thread? The area of Bushehr and the gap formed by the Armenian highlands would also need to be defended, and these regions don't have millennia of infrastructure built for them. That's 4 legions for the border, that same number could surely defend the shorter and more navigable Tigris with greater efficiency.
You're actually the first to bring it up so you can't really blame me for not addressing it sooner. Anyways, a Tigris border wouldn't give the entirety of Mesopotamia, but it would give the lion's share of it (and awkwardly bisect Seleukia-Ctesiphon). And given the actual frequency of Roman-Persian wars IOTL I don't think perpetual devastation is on the menu, the two powers traded more than they warred .
(in a period of 697 years of contact, they spent around 120ish years at war with each other, which is alot but not devastating to a region, as it wasn't to Northern Mesopotamia and Syria IOTL).
Caesar was able to do that because the Germans weren't patrolling the river and didn't have a riverine navy that could block an enemy build up. I'd suggest looking at the first page of this thread where I addressed this exact point. As long as the Romans have naval superiority on the river it's a solid defence against just about everything.
See above.
If the area doesn’t have a much infrastructure built for the defending army to march and garrison it,you think the same could be said about an attacking army?
RogueTraderEnthusiast has already addressed your points on Bushehr.
Furthermore,the Romans can likely raise additional legions out of Mesopotamia.
Covering the lion’s share of Tigris is good enough to allow the army on the opposite side to wreck the hell out of what’s on the other side.
Most of the Roman-Persian wars were limited to northern Mesopotamia and the eastern parts of Syria as you mentioned,but these areas are far from being the richest areas of Syria and Mesopotamia.There’s a massive reason why the richest part of Roman Syria is in the west and why the richest part of Mesopotamia is in the south.As to the claim about these areas not being devastated by war,I very much doubt this claim.
As long as the Romans have naval superiority?What the Roman will face are not low tech barbarians,they will be facing Persians who definitely did field navies of their own,not to mention far more experienced in the Tigris than them.The Romans simply can not guarantee naval superiority against the Persians here.Even if you aren’t attacked,you are still leaving out the highly fertile eastern bank of the Tigris to the Persians.