The joint history of the Eastern Roman Empire and the Sassanid Empire appears to be dominated by almost constant warfare. My understanding is that this weakened both empires to the point of making the rapid Muslim conquest of the entire Sassanid and large parts of the Eastern Roman empire possible.

Was there any significant obstacle to the two empires coming to a lasting peaceful arrangement? If so, was it "material" (e.g. stuff both needed to control) or "cultural" (e.g. the Romans never had to make lasting peace with anyone before, so didn't know how to), or some combination of both?

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    Both empires assumed that war meant strength and peace meant weakness. If nothing else, when you are at war, you know who your generals are fighting. If you are at peace, the generals may choose to use those troops to rebel, or engage in policies not endorsed by the state.
    – MCW
    Commented Apr 3, 2017 at 12:45
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    Really? I doubt that any rational actor would engage a minor target when an empire posing an existential threat was on the doorstep. Proxy wars were common. The question presumes the modern assumption that peace is better than war - that is not shared at the time - war & conquest were a necessary part of national income.
    – MCW
    Commented Apr 3, 2017 at 12:58
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    Not enough for a definitive answer, but an issue was that both Empires did have client states along their common borders (e.g. Armenia). Often wars would be caused by escalation of internal conflicts in those countries; for example a pro-Persian clan dethroning a pro-Roman king and the like.
    – SJuan76
    Commented Apr 3, 2017 at 13:01
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    @SJuan76 - true - proxy wars are a standard way for two empires to export conflict to a client kingdom where it has less impact on domestic support.
    – MCW
    Commented Apr 3, 2017 at 13:06
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    Mark C Wallace - can you cite any sources for your contentions as to the 2 empires' reasons for fighting so often? I am no expert on this, but hope someone else might know, is there any evidence that religious differences between Persian Zoroastrianism and late Roman Christianity, or even the (usually) more tolerant paganism Roman paganism had anything to do with it? Also, do we know if the border regions of Mesopotamia (once a or the major centre of world civilization) and Syria were still particularly rich and lucrative areas to want to control?
    – Timothy
    Commented Apr 3, 2017 at 16:21

2 Answers 2


Pre-modern empires are generally driven toward territorial expansion. Obviously the territories of the Mediterranean and Central Asia each brought a range of different resources that the opposing empire would like to control. When two large rivals get in each others way, conflict is almost inevitable. It is tempting to draw comparisons with other bipolar situations in the ancient world, like Athens and Sparta. If one were significantly weaker then the other, the rival would have been erased much sooner. But when two large powers emerge, a stable situation of lower-level conflict can emerge and will continue until one gets the upper hand.

However, as again is more generally the case, the two civilizations were not in a constant state of all-out war. In that sense, they did achieve a high degree of peaceful co-existence at various moments in time. An interesting illustration of that is the degree of cultural mixing that occurred in the borderzone between the two empires. Quoting an article from The Metropolitan Museum of Art:

The Sasanian empire expanded its geographic scope dramatically under Shapur I (r. 241–72), when its lands stretched into Central Asia and stopped just short of the Mediterranean in current-day Syria. This began a centuries-long cycle of expansion and retraction, which placed the Sasanians in direct conflict with Rome, and later, Byzantinum. Much of the eastern Mediterranean became a buffer zone between empires, which presented opportunities for rich cultural exchanges in between devastating military battles. Trade and the movement of people resulted in a distinctive frontier culture in towns like Palmyra, Dura Europas, and Resafa that mixed Mediterranean-Roman and Hellenistic-Parthian elements. Dress preferences reflect these contacts. Sculptures from Palmyra, for instance, depict some men wearing pants associated with eastern dress styles, while others don the togas of Roman elites.


But they did make a lasting peace...in 628 when Kavadh II agreed to Hieraclius' terms. History took a sharp turn a few years later, when the Arabs conquered the Sassanid Empire, but the Arabs didn't impose the settlement of 628.

Perhaps you meant to ask why they didn't make a lasting peace much sooner?

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    Kavadh II agreed to end the war that Kavadh I began in 502, which had paused with an Eternal peace treaty in 532, restarted in 540, paused again with another peace treaty in 562, kicked off again in the 570s, paused again in the 590s, kicked off again in 602, and ran until 628. Kavadh II's peace only lasted because the Sassanid Empire collapsed before hostilities could resume! Commented May 15, 2019 at 18:03
  • Of course the resumption in 602 was only because of a coup in the Roman Empire, so part of the problem was the problem that peaces between empires are personal between the emperors. Or possibly one could say that Maurice's army preferred to fight Persians rather than deal with cold Balkan winters fighting against Slavs and Avars....
    – C Monsour
    Commented May 15, 2019 at 22:30
  • However, the peace of 628 came about through a fantastic campaign by Hieraclius and defensive collapse by the Persians. It might not have lasted forever but, being based on a decisive military outcome, it was about as lasting a peace as you were going to get, absent total annihilation of one party.
    – C Monsour
    Commented May 15, 2019 at 22:39
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    So the Sassanid Empire was defeated by the Eastern Roman Empire, and in less than a generation had ceased to exist in the Islamic Conquest. That's not quite the same thing as a 'lasting peace'. Commented May 15, 2019 at 23:03
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    Every peace is a lasting peace until it isn't. Commented Jun 14, 2019 at 19:44

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