Persian power peaks under the long reign of Sassanid king Shapur II, who has recaptured Mesopotamia from Rome and subdued the Kushans in present Afghanistan to annex their kingdom.

After a long campaign against the Chionites (353-358), Shapur is ready for a second encounter with Rome and sends an ambassador to Constantius, bearing presents and a letter wrapped in white silk.

This letter reads, in part, “I Sapor, king of kings, partner of the stars, brother of the sun and the moon, to Constantius Caesar my brother send much greeting … Because … the language of truth ought to be unrestrained and free, and because men in the highest rank ought only to say what they mean, I will reduce my propositions into a few words … Even your own ancient records bear witness that my ancestors possessed all the country up to the Strymon and the frontier of Macedonia.

And these lands it is fitting that I who (not to speak arrogantly) am superior to those ancient kings in magnificence, and in all eminent virtues, should now reclaim.

But I am at all times thoughtful to remember that, from my earliest youth, I have never done anything to repent of.”

When Constantius politely refuses to hand over these lands, …