Why is it that the Sassanids collapsed within a few years of the initial Muslim conquest but the Roman Empire was able to hold on for centuries after the loss of Egypt, Syria and Palestine in the 630s-40s, and remain a great Mediterranean power for 4 of them, until their defeat at Manzikert in 1071?

by Tariq-ibn-Ziyad

I know that at the time that the Caliphate was beginning to expand the Romans and the Persians were exhausted and spent in terms of money, men and morale, having been at war from 572 to 591 and then again from 602 to 628, but Sassanid Persia was essentially gone after the Battle of Nahavand in 642 while the Romans (ie the Byzantines, but I’ve read that is an incorrect term to describe the Roman Empire after it’s capital was moved to Constantinople and Greek replaced Latin as the primary language) held on after their loss at the Battle of Yarmouk in 636, the conquest of Egypt etc. and for much of that time, until 1071 they remained a great power.

This is surprising because it seems that the Persians did better for themselves than the Romans in their last war, and that the Persian state was much more functional than Rome with its constant civil wars, governmental intrigue and perpetual threat of invasion into the Balkans and Greece by Slavs, Huns, Avars, Goths etc and so one would think that it was the Sassanids who would have been better positioned to put up resistance and hold on for some time.

PrincedeReynell

Because Persia under the Sassanids was not that stable in the later years before the Islamic conquest.

In the decade before the Arab conquest the Persian Empire had gone through 15 deferent Shahenshas:

1)Khosrow II (592-628)

2)Kavad II (628) murdered his father, Khosrow II.

  1. Ardashir III (628-30)

4)Shahebaraz (April-June 630)

5)Khosrow III (630) rival Shah to Shahebaraz

6)Boran (630) overthrew her brother.

  1. Shapur V (630) deposed Boran

  2. Peroz II (630) rival Shah to Boran

  3. Azarmidokht (630) deposed her cousin Shapur V

  4. Hormizd V (630) rival Shah to Azarmidokht

  5. Hormizd VI (630-32)

  6. Khosrow IV (630-36)

  7. Furrikhzad Khosrow V (march- April 631) rival Shah

  8. Boran (631-32) second reign

  9. Yazdegerd III (632-52) last Shahensha before Rashidun invasion.

Meanwhile during the same time frame the Roman Empire on had one three claimants to the throne- Maurice, Phocas, and Heraclius.

Phocas murdered Maurice and fought a two year revolt against the Heraclian dynasty and was overthrown by Emperor Heraclius. Heraclius would then fight several wars with the Sassanids only to have things go "status co antebellum" before the Rashidun invasion.

Maurice (582-602)

Phocas (602-10)

Heraclius (610-641)