Rome vs. Persia: In the 610s, Persia was racking up victories, and in the 620s, Constantinople began reversing them. By 630, under pressure of war expenses, both empires had meddled in the other side’s revolutions, supporting either a rebel or the son of an overthrown ruler. It happened more than once, so that for being enemies, both at times were under obligations to the other. Heraclius had been Roman Emperor long enough now to seem pretty stable, but Persia was a mess.
The Persian king who received Muhammad’s letter was Khosrow II, and he bore the brunt of the Roman Emperor Heraclius’s victories. War had disrupted his economy and taxation, and of course had also made him spend a lot on fielding several armies. He came down with dysentery in the field, and named a successor. He passed over his oldest son and chose a younger one. This decision became one more vulnerability that Heraclius could exploit; the Romans probably assisted in some way when the oldest son overthrew his father and brother in a sudden coup. That’s the coup that they heard about in Yemen.
Khavad II executed his brother, of course. But he went further, chasing down all of his half-brothers and other male relatives, about twenty targeted family deaths. He made peace with Heraclius and agreed to give back the fragment of the True Cross that the Persians had removed from its basilica in Jerusalem. Heraclius restored the relic with pomp and devotion in 630. But Khavad II ruled for less than a year, then he died, leaving a son who was only seven. In a stable period, men can rule for a child, but in an unstable time that won’t happen. A man who has just killed all of his brothers can’t really expect the family to be loyal to his young child. A rebel general seized power.
On the eastern edge of the Persian lands, a new force was taking bites off their territory. This new force was an early wave of Turks, who would become a major issue in the Muslim Empire as well. A Turkish army seized Tiflis, the capital of Georgia, and killed everyone. When the Persians sent out an army, the Turks managed to trap and kill them, too. These losses were too heavy for a newly-crowned rebel general-king to sustain. He was assassinated, and the previous royal family was sought out.
But Khavad II had killed so many of his brothers that it was hard to find anyone to make into a king. Two of his sisters served as kings! By the time of Muhammad’s death in far-off Medina, both sisters had ruled and died, and the family then tried out five other relatives as kings. Yazdgerd III became king while Arabia was fighting out its Wars of Apostasy.
When a country falls into a situation like this, central government loses control. Taxes are not collected and transported reliably, so the capital is short of funds. Strongmen in various regions seize control, partly because someone has to be in charge to prevent chaos. By the time Yazdgerd III was calling himself king, there was not much Persia left to rule over. Turks were invading Georgia and Armenia, and most Persian cities had little connection to Ctesiphon. The Persian military had been devastated by its many losses and the major rebellion of its general. The great advantage of an empire is that it can field a very large army, supported by taxes, and able to move anywhere that it’s needed. Persia had lost most of this advantage by 633, when the Arabian civil war wound down.
Persia tended to be more decentralized than the Eastern Roman empire, too. Its nobles and king moved about among their country houses, rather than gathering in a large city like Constantinople. They had cities, but these were not built up quite the way they were to the west. The religion, too, tended to decentralization. Zoroastrian religion had fire temples, but the most important fire temples were not in central places, nor did they have large buildings. Hugh Kennedy suggests Zoroastrianism may have been an elite religion mostly followed by the aristocracy. If so, there were many peasants without any firm tie to a native religion.
Persia also had large Jewish and Nestorian Christian populations. Jews came to the region in the original Babylonian captivity, and then again after the destruction of Jerusalem. Nestorians had been fleeing eastward since the church council that outlawed their theology. It’s likely that both religions had found willing converts among the native Iraqis, the working poor who were left out of the fire religion. The Assyrian Christian Church was strong at that time. There were probably also many who practiced some sort of close-to-the-earth animism, which seems to be the natural religion of most of the world.
The Roman and Persian empires had in common a trait that left them vulnerable to Muslim conquest: the ruling class was alienated from the peasants, who often spoke another language. Persia’s society was highly stratified. The elite spoke Farsi, but the peasants of Iraq spoke Aramaic, as did the peasants of Syria. Their culture and religion were set up to offer the peasants and working class nothing. Islam, on the other hand, was set up as an egalitarian system that welcomed everyone. It offered everyone a way to participate by prayers and alms.
- The War of the Three Gods, by Peter Crawford.
- The Great Arab Conquests, by Hugh Kennedy