Pathogenesis: A History of the World in Eight Plagues

by Jonathan Kennedy

The start of the seventh century was a particularly violent time in their relationship. Initially, the Sasanians, who now controlled Persia, were successful against the plague-weakened Byzantines. They conquered Jerusalem in 614, along with much of the Middle East, and took the relic of the True Cross—that is, the cross that Jesus was supposedly crucified on—as a trophy; between 618 and 621 they gained Alexandria and the province of Egypt, which provided Constantinople with most of its grain. The Sasanians even besieged the imperial capital in 626 but failed to capture it. Then, in 627, the tide turned: the Sasanians were badly hit by an epidemic which is said to have killed half the population, including the emperor Sheroe, who gave his name to the plague.[64] In the next couple of years the Byzantines reclaimed Jerusalem and the cross, then reconquered Alexandria and the rest of Egypt.

It is interesting that the Sasanians were able to expand their influence during this time. While they were busy fighting the Byzantine Empire, Muhammed and his followers were expanding Islam across Arabia. By 630, an Islamic state was established in Mecca which would later challenge the Sasanian Empire. If the plague had not weaked the Byzantine Empire, the Sasanians would have likely focused on subjugating the fledgling Islamic-state instead.