Furthermore, the fall of Khosrow II also culminated in a civil war lasting four years, with the most powerful members of the nobility gaining full autonomy and starting to create their own government.

[4] He was succeeded by his eight-year-old son Ardashir III, who was killed two years later by the distinguished Sasanian general Shahrbaraz, who was in turn murdered forty days later in a coup by the Pahlav leader Farrukh Hormizd, who installed the daughter of Khosrow II, Boran, on the throne.

[6] The most powerful magnates in the empire, Rostam Farrokhzad[a] and Piruz Khosrow, now threatened by their own men, eventually agreed to work together, and installed Yazdegerd III on the throne, thus putting an end to the civil war.

[4][3][10] Yazdegerd, however, did not have the authority required to bring stability to his extensive empire, which was swiftly falling apart due to ceaseless internal conflicts between the army commanders, courtiers, and powerful members of the aristocracy, who were fighting amongst themselves and wiping each other out.

[3] The governors of the provinces of Mazun and Yemen had already asserted their independence during the civil war of 628–632, thus resulting in the disintegration of Sasanian rule in the Arabian Peninsula, which was uniting under the banner of Islam.

Indeed, during the first years of his rule coins were only minted in Pars, Sakastan, and Khuzestan, approximately corresponding to the regions of the southwest (Xwarwarān) and southeast (Nēmrōz), where the Parsig was based.

[14] Even in the south Yazdegerd's rule was not seemingly secure; a Sasanian claimant to the throne, Khosrow IV, minted coins at Susa in Khuzestan around this time, which he would do till 636.

[16] The circumstances were so chaotic, and the condition of the nation so alarming, that "the Persians openly spoke of the imminent downfall of their empire, and saw its portents in natural calamities.

Yazdegerd took his treasury, and along with 1,000 of his servants fled to Hulwan in Media, leaving Rostam Farrokhzad's brother Farrukhzad in charge of Ctesiphon.

[23] Al-Tabari emphasizes this, stating that after the fall of Ctesiphon "the people... were about to go their separate ways, they started to incite one another: 'If you disperse now, you will never get together again; this is a spot that sends us in different directions'.

[11] The army that Yazdegerd sent seemed such a serious threat that it led Umar to combine the Arab forces of Kufa and Basra under Al-Nu'man ibn Muqrin and send them against the Sasanians with reinforcements from Syria and Oman.

It resulted in major losses on both sides, including the death of al-Nu'man ibn Muqrin and the Iranian generals Mardanshah and Piruz Khosrow.

[11] After the Sasanian disaster, Yazdegerd fled to Isfahan, and raised a small army under a certain military officer named Siyah, who had lost his property to the Arabs.

[28] As he continued to suffer defeats from the Arabs, he again sent envoys to China, in 647 and 648, in order to “seek assistance from the Chinese court with the hope to form a new army".

All the nobles curse Mahoe and wish him the same fate.Regardless, the death of Yazdegerd marked the end of the Sasanian Empire, and made it less difficult for the Arabs to conquer the rest of Iran.

An empire–which had a generation earlier briefly conquered Egypt and Asia Minor, even reaching as a far as Constantinople, fell to a force of lightly equipped Arabs that were used to skirmishes and desert warfare.

The heavy Sasanian cavalry was too sluggish and systematized to contain them; employing light-armed Arab or East Iranian mercenaries from Khorasan and Transoxiana would have been much more successful.

His funeral and the construction of a mausoleum for his body near Merv was organized by the Nestorian bishop Elijah - in memory of the fact that the Shahanshah's grandmother Shirin was a Christian.

Mahoe, for his part in the murder of the Sassanian king, had his arms, legs, ears and nose cut off by the Turks, who eventually left him die under the scorching summer sun.

[34] Whether this event was factual or not, it emphasizes that the Christians of the empire remained loyal to the Zoroastrian Sasanians, even possibly more than the Iranian nobles who had deserted Yazdegerd.

[4] Yazdegerd was well educated and cultured, but his arrogance, pride and inability to compare his demands with the real situation led to him constantly falling out with his governors and his influence diminishing as he, pursued by Arabs, moved from one city to another.

At each new place, he behaved as if he was still the all-powerful monarch of the kingdom, and not an outcast running away from enemies, which, combined with his military failures, turned many of his most loyal subjects away from him.