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The Fall of the Sassanid Empire

Andrew is an avid reader who enjoys researching and discussing history with others.

A map of the Sasanian Empire at its greatest extent.

A map of the Sasanian Empire at its greatest extent.

What Was the Sassanid Empire?

The Sassanid Empire was the last non-Islamic empire that ruled over Iran. The empire was established in 224 AD, after the leader of the House of Sassan, Ardashir, defeated and overthrew the Arsacid dynasty that was ruling over the Parthian Empire. The Sassanids quickly established their power and became a fierce rival for the Roman and later the Eastern Roman Empire. Ardhasir’s son Shapur defeated and even captured Roman Emperors, like the unfortunate Valerian. Despite the many wars the Sassanids and the Romans fought against one another, the borders of the two empires changed little during their 400 years of rivalry.

Most of the conflicts were fought over the control of Armenia and the border towns and fortresses. During the weaker periods of the Persians, the Romans were able to march on the Sassanid capital and even sacked Ctesiphon. While during the weaker periods of the Romans, the Sassanids rampaged through Syria and Roman Armenia.

Historians of the period regard the Sassanids as a much more dangerous foe and formidable threat to the rich eastern provinces of Rome than their Arsacid predecessors. It is a correct judgment, no doubt, considering the much better military record the Sassanids had against the Romans than the military record of their predecessors.

This better military record led historians into believing that, unlike the more or less feudal state of Arsacid Parthia, the Sassanid Empire, just like Rome, was a centralized state.

Was the Sassanid Empire a Centralized State?

Some historians still hold this view, but just like always with ancient history, a revisionist school challenges this view. Professor Parvaneh Pourshariati openly challenged this view in her book The Decline and Fall of the Sassanid Empire.

She believes that rather than a strong centralized state, the Sassanid Empire continued the quasi-feudal structure of their predecessors and the Parthian clans who were just below the Sassanid dynasty in the hierarchy of the empire remained very powerful and influential all through the existence of the empire.

I have read books sustaining both views, and for me, the decentralized Sassanid Empire seemed more fitting, so I will use the ideas of that school.

According to this school, the power of the monarch was from time to time challenged by the powerful nobility, who had more than enough power to dominate or even depose weak-willed rulers. This status quo was changed during the late 5th and early 6th centuries when Shah Kavad used the Mazdekite movement to curb the power of the nobles.

Kavad succeeded in curbing the power of the nobles and the priests, and once the Mazdakite movement served its purpose, he turned on them. His son Khosrow followed his father’s path and continued his reforms. He tried to further improve taxation, the armed forces of the state, and the empire’s administration.

How much these reforms succeeded is difficult to know, but judging by the fact that the grandees of the empire continued to serve in the leading positions, probably the reforms had rather limited success.

The reform-minded Khosrow I was followed by his harsh son, Hormizd. According to historians, Hormizd purged the empire’s nobility and ordered several thousands of them to be killed or imprisoned. His greatest general, Bahram Chobin, rebelled against him after Hormizd humiliated the general and marched on the capital.

The court of Hormizd turned on the Shah, deposed and blinded him, but the offer of putting Hormizd’s son Khosrow on the throne was not good enough for Bahram, who took the throne for himself.

Khosrow, with the assistance of his uncles, fled to the court of Emperor Maurice. Maurice agreed to help restore Khosrow to his throne, though he asked for the cessation of some territories. The combined armies of Maurice and Khosrow’s uncles defeated Bahram, who fled to the Turkic Khagan, who shortly afterwards had him assassinated on behalf of Khosrow.

Despite the help Khosrow received from his uncles, he did not forget that they turned on his father when it suited them. Khosrow had one of his uncles, Vinduyih, killed and probably had similar intentions with his other uncles, but Vistahm rose in rebellion against his nephew.

This rebellion lasted for several years before the forces of Khosrow defeated his uncle. Still, the power of the Ispahbudhan family was too great to be simply erased, and the sons of Vistahm continued to occupy important military and administrative positions in the following decades.

Peak of the Sassanid Empire and Downfall

A few years of peace followed, but when Khosrow’s benefactor Maurice was murdered by a mutinous army commander, Khosrow used his death as cassus belli to invade the Roman East. His invasion was helped because several armies of the Roman East rose in rebellion against the usurper Phocas. Khosrow claimed that he intended to reinstate the son of Maurice, Theodosius, to the throne in Constantinople. However, historians doubt whether it was the son of Maurice or just an impostor used by Khosrow to justify his claims.

The Byzantine-Sassanid War that broke out in late 602 lasted until 628, by far the longest and most devastating war that the two empires ever waged on each other.

The Sassanids took over most of the Roman East in the first two decades of the war. By 620, the Persian armies conquered Syrian, the Levant, Egypt and the armies of Khosrow raided as far as the shores of the Bosphorus. The Byzantine infighting further helped the Persian progress. In 608, the governor of Africa, Heraclius the elder, challenged the rule of Emperor Phocas. In a two-year civil war, he and his allies overthrew Phocas and placed Heraclius the Younger on the Imperial throne.

Emperor Heraclius led a counterattack in the early 610s against the Persians. Still, he was defeated near Antioch, and his defeat was the main reason the Persians were able to overrun most of the Roman provinces. It took Heraclius several years to assemble, equip and train another army. Still, by 622, the army was ready, and the emperor took command in person to lead it against the Persian heartland.

Heraclius, for 5 years, campaigned in the Persian heartland and defeated the Persians in nearly every one of their encounters. His battlefield successes and the failed siege of Constantinople in 626 undermined the support Khosrow had. The nobles turned on the Shah in February 628 and overthrew him in a palace coup. They placed one of the sons of Khosrow, Kavad, on the throne, while the rest were all executed, either by the ruler's orders or the nobles.

A peace treaty was signed by Kavad II, according to which the Persians evacuated all their conquered territories. A plague hit Mesopotamia not much later and killed half the province's population, Shah Kavad II included.

He was followed on the throne by his infant son, but the greatest general of the empire, Sharbaraz, rebelled and deposed the child. He took the throne himself. Sharbaraz was assassinated not much later, and during the next few years, a civil war erupted in the Sassanid Empire, and over 10 rulers succeeded one another in short succession.

While the Persians were too busy to tear each other to pieces, the Prophet Muhammad united the Arab tribes under the banner of Islam.

By the time the Persian Civil War was over, and a new ruler Yazdegerd was placed on the throne, though he was little more than a child at the time, the Arabs were a real threat.

The Arabs started to attack Mesopotamia in the 630s. After their decisive victory at the Battle of al-Qadisiyyah, the Arabs conquered Mesopotamia. The Arabs defeated the remaining Sassanid loyalists at Nahavand in 641. From this moment on, the power of the empire was broken.

The official date of the Sassanid Empire is dated 651, when Shah Yazdegerd was killed. The Sassanid dynasty was the last pre-Islamic house to this date that have ruled over Persia; during its golden years, the Sassanid Empire was every bit the equal of the Eastern Roman Empire, but as it happened to many other great empires, overextension through wars and civil strife undermined the foundations of it and left it vulnerable to foreign attacks.


Pourshariati, Parvaneh. (2017). Decline and Fall of the Sasanian Empire: The Sasanian-Parthian Confederacy and the Arab Conquest of Iran. I.B. Tauris.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2022 Andrew Szekler