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Two defeats at the hands of the invading Arabs were enough to put an end to the Iranian domination of Mesopotamia and the Iranian plateau, which had lasted for 1200 years (apart from the brief interval of Greek rule in the 4th and 3rd centuries BC).

Qadisiyya in AD 637 lost them Mesopotamia (Iraq) and their capital at Ctesiphon on the Tigris (Arab al-Mada'in).

Nihawand in AD 642 opened up the entire Iranian plateau to the Arab victors.

At the same time the Arabs took Syria from the Byzantines - though the conquest of Anatolia was beyond them.

Why did the Sasanian empire crumble so quickly?

Traditional explanations include:

  • The Sasanians had been weakened by 250 years of conflict with the Byzantines, and by internal squabbles. The heavy Savaran cavalry was less manoeuvrable than the lighter-armed Arabs. Muslim sources grotesquely exaggerate the size of the Persian army (like Herodotus did when Xerxes invaded - a boastful device to make victory seem more heroic).
  • The Sasanian royal family was no longer in control (the last kings had been generals): did this weaken the loyalty of their subjects? Certainly Yazdegird found them unhelpful when he fled to Chorasmia.
  • Khusrau I's reforms had not yet "bedded in" - there was opposition to political and miltary changes, and the "state religion" was unpopular among ordinary people. The "spahbad" system meant the Arabs only had to defeat the western army for the whole empire to be exposed.
  • Corruption was rife in the exhausted ruling class, and the priesthood (Magi).

A more likely explanation

Some or even all of the above may have been true - but the Byzantine empire also suffered two defeats (Ajnadayn 634 and Yarmuk 636) and was no less troubled by corrupt and unpopular priests and rulers. Yet Byzantium survived - for 800 more years. The simplest explanation is probably the best: it was the Sasanian's bad luck that Iraq lay on the Arabs' doorstep, and that the Sasanian capital was in Iraq. Constantinople was secure in its remoteness, and Anatolia's terrain, though regularly invaded, was hostile to a desert people. Had the Sasanian capital - with its treasury and administration been on the Iranian plateau, the other side of the Zagros, at Rayy (Tehran), say, it too could have held out, and coped with the loss of a couple of battles.

Resistance and fight-back: the last Sasanians

The family of Yazdegird III, the last Sasanian king of kings, made several unsuccessful attemts to regain a foothold in Iran. His son Peroz may briefly have occupied a corner of Seistan, and even aided a rebellion in Chorasmia - but the sources are not clear. Peroz's son Narseh was with a Chinese force supposedly sent to confront the Arabs, but which accomplished nothing at all in 20 years. A grandson of Yazdegird called Khusrau is recorded in Chinese accounts with an army of Turks trying to "recover his kingdom" (AD 728). He failed to do so, and, probably, returned to an honoured retirement in China like his father and grandfather.

Many Iranian cities made the conquest difficult: there was widespread resitance to the Arabs. Hamadan in Media rebelled, and Istakhr in Persis, home city of the Sasanian dynasty, rebelled several times - even when there had been punitive retribution after a siege in 650 or 651, in which thousands were killed, according to Arab sources. But for the most part - with the exception of Tabaristan (between the Alborz mountains and the Caspian) and parts of Chorasmia (Khorasan) - the Iranian plateau, as well as Iraq, was in Arab hands by the time Yazdegird III was murdered in AD 651.

Dome of the Rock

The oldest surviving mosque: the Dome of the Rock, Jerusalem, built by the Umayyad caliph Abd al-Malik (685-705). Photo AMW

The Umayyads (AD 661 - 750)

As well as tension between those who accepted Abu Bakr's caliphate and those who supported Ali, there was also rivalry between former Byzantine areas of the Arab empire (Syria), former Sasanian areas (Iraq), and the original homeland in Hijaz (Arabia). Possibly these rivalries had existed from the very beginning, corresponding to three different communities, each with a claim to be the legitimate heir of Muhammad. Syria emerged supreme militarily, and claimed authority over the rest. The murder of Uthman, the third Caliph and a member of the Umayyad family, led to civil war in which Ali's forces were eventually overcome by the Umayyad Muawiyah, who proclaimed himself caliph. The Umayyads were an old family from Mecca, from a different branch of the Quraysh, Muhammad's tribe. Hostility between the two branches went back many generations.

Two groups were implacably opposed to the Umayyad takeover: the Kharijites, who believed the caliph should be democratically elected by righteous Muslims - and removed if he acted unjustly, and the Shi‘is (derived from shi‘iat meaning party; that is Shi‘iat Ali, "The Party of Ali") who believed the caliph should be a blood descendant of Muhammad, or at least a member of his family. The Kharijites had been responsible for the assassination of Ali, but lacked the military clout to challenge Muawiyah, though they remained an irritant. The Umayyads moved their capital westwards to Damascus in Syria - away from Kufa, Ali's capital near Ctesiphon on the Euphrates. They took over much of the administrative machinery from their Byzantine predecessors - but were accused of favouring Arabs over other Muslims, and also of becoming corrupted by power and luxury. The caliphate became hereditary in their family, alienating non-Syrian, and non-Arab Muslims, as well as the Shi‘is. Mecca reverted to being a religious centre and a destination for pilgrims. The Umayyads and those who believed that what was most important for Muslims was not whether the caliph was descended from Muhammad, but their adherence to the sunna, the body of custom deriving from Muhammad's words ands deeds (hence known as Sunnis)

The Shi‘is never accepted the Umayyad leadership, and have continued to regard the first three caliphs as illegitimate: they were ritually cursed in Shi‘i mosques for many centuries. A revolt led by Ali's son Imam Husain was crushed at Karbala in AD 680 by Caliph Yazid - Husain was killed and his supporters massacred. There were other violent outbursts and rebellions: the Shi‘i ideology began to take shape as martyrs were made and grievances piled up. Opposition - originally in Iraq - began to organise.

Karbala shrine

The Shrine of Husain in Karbala, Iraq, in 1975

Home and Away

At home the Umayyads were confronted by civil wars, and numerous revolts, which eventually ended in the overthrow of the dynasty. Abroad the Arab empire continued its expansion, but, although for a time territorially larger than the Persian empire at its greatest, it soon had to accept its limits. Egypt was won over; North Africa was conquered and was intermittently rebellious, but stayed under Umayyad control. Spain was annexed, but expansion beyond the Pyrennees was halted by the Franks at the Battle of Tours in AD 732. There were numerous attacks on the Byzantine empire in Anatolia, and on Constantinople - which achieved nothing. Expansion north of Armenia across the Caucasus was stopped by the Turkic Khazars. The north east of the Iranian plateau (Chorasmia and Transoxiana) was subdued - but it was from here that the Umayyads' nemesis eventually came. The Arabs invaded India but were soon driven out.

Two great mosques date from the Umayyads - the Dome of the Rock (above) in Jerusalem (completed in 692) and the Great Mosque in Damascus (built under al-Walid).

The Umayyads eventually lost their Syrian-based caliphate to the Abbasids - but continued to rule in al-Andalus (Andalucia), which remained under Arab control until AD 1051. There are many impressive reminders of their time in Spain, especially the Great Mosque in Cordoba (where los reyes cattolicos plonked a cathedral in the centre), and the Alhambra in Granada.


The Great Mosque in Cordoba, Spain. Photo AMW.


Vast numbers of slaves were acquired by the Arab conquerors - the Arabs were very much a minority in the lands they had occupied. Most of these slaves worked in the house, or as traders and craftsmen (and prostitutes), and therefore had close contact with their masters. Unsurprisingly, many of them adopted their conquerors' religion - and soon non-Arab Muslims were in the majority. Slaves were often freed - but instead of becoming equals, they were still treated as slaves, with "massive prejudice" against them. They were barred from positions of responsibility, could not marry Arabs, and had to worship at their own mosques. Legally they were mawali, clients of their former masters, though their legal status meant little. However, they fought on both sides in the civil war between Ali and Muawiyah - and played an important part in the revolt which seized Kufa in 685-7.

Many of these mawali were Iranians - and Arab leaders began to fear their increasing numbers and influence. People said:

It might be better to kill nine out of ten captives than to have slaves. They will not remain loyal and they will ruin your lives

But slaves continued to come, and continued to be freed. As prejudices lessened, within a few generations the peoples of the former Sasanian empire were following Islam, speaking Arabic, and marrying Arabs. The government, however, and its army were still exclusively Syrian, and attuned to the Arabs' desert past rather than their more multi-cultural present.

The Arabs did not persecute Zoroastrians - although fire-temples were destroyed. For practical reasons, they were accepted as "Peoples of the Book" (according to the Quran strictly only Jews and Christians), but some common beliefs - as well as evading the tax paid by mon-Muslims (the jizya) - encouraged conversion.