That's ridiculous. Ctesiphon, the Persian Empire's capital, was sacked on numerous occasions by Roman armies. Has any Persian army ever actually gotten past the Roman hinterlands, let alone be able to sack Italia itself? One of the few advantages the Persians had over the Romans was their superior calvary ... especially light units and later cataphracts. But in terms of infantry, armor, weaponry, and siege equipment, the Roman Army was much better equipped than the Persian forces.
The comparison you're making is ridiculous. Italy was too far away for the Persians to realistically pose any threat to it. The Persians did on the other hand sack Roman cities like Antioch, Edessa, Caesarea. Under Khosrow II they practically wiped out the Eastern Roman army took control of Syria, Egypt and Anatolia AND reached Constantinople itself, not bad for a force outmatched quantitively and qualitatively eh?
Now as for Roman military doctrine, go pick up any book you want, the Romans gradually shifted from infantry based armies to cavalry based ones which historians themselves acknowledge heavily resembled Persian ones, in fact they were extremely similar by the time the Muslim armies emerged on the scene. The Romans literally modelled their armies on those of the Sassanids.
Roman infantry was superior to most of the Sassanid infantry who were peasant levies, but the Daylamites from northern Persia were considered equals and praised by the Romans themselves. Go look em up. They acted as guards for the emperor himself.
And let's not even talk about infrastructure ... the Roman aqueducts were centuries beyond whatever Ancient Persia had to offer. Saying that the Persian Empire was more technologically advanced than that of Rome is simply ignorant.
The Persians had advanced irrigation systems called Qanats that were used for thousands of years more than a mathcn, they built huge sophisticated walls like those of Gorgan, their fortresses were on par with those of Rome. They even used poisionous gas against the Romans at the siege of Dara. I didn't say more advanced, I said rivals. And YOU must be ignorant to deny it, they held Rome at bay for centuries and forced it to pay tribute, yet you're so arrogant you refuse to accept Persia as an equal.
And please provide factual evidence that the Romans treated Persians as equals ... AFAIK, the Romans thought the Persians were barbarians (just like the Germanic hordes).
Yazdgerd I was asked by Emperor Arcadius of Rome to become guardian of his son, the future Theodosius II, i've never heard a Roman emperor ask a Germanic chief to do the same, have you?
The Roman emperor Carcalla asked for a Parthian princesses hand in marriage and when refused declared war.
Constantine I referred to Shapur II as "My brother" in a letter to the latter. Did the Roman emperors even consider the Germanic chiefs worthy of personal correpondence let alone refer to one of them as a brother? Persian and Roman queens referred to one another as sister, and gifts were exchanged between both parties too.
EDIT: Almost forgot, Khosrow II married Maria, daughter of emperor Maurice. His son by Maria, Kavadh would later go on to be emperor. Barbarians my ***.
Persia never stepped a foot into Rome. Rome destroyed persian Capital, killed persian crown Prince and made Persia pay Tribute. Persia had no aquaducts, No advanced streets, no concrete.
Rome was too far, the Persians sacked plenty of major cities in the Roman occupied near east. I know which prince you're on about, but firstly, that was in battle, not execution, and that was because Persian kings usually fought in battles. The Persians on the other hand captured an emperor and skinned him and turned him into a trophy.
The Persians had Qanats. Obviously they had streets. Not sure about conrete, but they clearly used effective materials since many of their cities/monuments can still be seen today.