The eastern Roman Empire was half alive, half gobbled up by the Arabs. And Iran — well, it had been wiped out as an enlightened, ancient empire a century before, in 651. After that, the Arabs took a long rest on the borders of Sogd modern-day central Asia, with its capital in Samarkand, which they began to conquer only in 712.
Why the rivalry? Why did the conquerors the Arabs so loathe the conquered the Iranians? That’s where the eighth century comes in. A hundred years after the Arabs destroyed Iran, their own empire, which stretched from Spain to the Chinese border, was a teetering wreck, being devoured from the inside by rivalries and bad government.Then, in 747, a revolt began in Iran that would eventually overthrow the Umayyad dynasty, replacing it with the Abbasids. The Abbasids would go on to build Baghdad and rule the huge Islamic caliphate for 500 years — until the arrival of Genghis Khan and his Horde.Yes, the Abbasids were Arabs, but their scribes, builders and literati were Iranians and the Arabs who cared to learn from them. As a result, the Iranians gradually all but took over their conqueror’s empire from the inside
Here is the crucial bit: The Arab-Iranian divide is far more than cultural. In the eighth century, subjugated Iran was also abandoning its ancient religion — Zoroastrianism — and creating its own, unique strand of Islam, Shiite, that stood in opposition to the dominant Sunni strand favored by the Abbasids.
A historian would tell us to remember that today’s conflict in Syria can be traced back to an Arab-Iranian — Sunni-Shiite – – rivalry that is 13 centuries old