with other matters, the Parsig, dissatisfied with the regency of Rostam, called for the overthrow of Boran and the return of the prominent Parsig figure Bahman Jaduya, who had been dismissed by her. Boran was killed shortly after; she was presumably strangled by Piruz Khosrow. Hostilities were thus resumed between the two factions. Not long afterwards, both Rostam and Piruz Khosrow were threatened by their own men, who had become alarmed by the declining state of the country. Rostam and Piruz Khosrow thus agreed to work together once more, installing Boran's nephew Yazdegerd III (632–651) on the throne, and so putting an end to the civil war. Accession of Yazdegerd III and end of the civil war Yazdegerd was crowned in the Anahid fire-temple in Istakhr, where he had been hiding during the civil war. The temple was the very place where the first Sasanian shahanshah Ardashir I () had crowned himself, indicating that the reason behind Yazdegerd's coronation at the same place was due to hopes for a rejuvenation of the empire. He was almost the last living member of the House of Sasan. Most scholars agree that Yazdegerd was eight years old at his coronation. At his accession, he assigned Rostam with the defense of the empire, telling him "Today you are the [most prominent] man among the Persians." Although being acknowledged as the rightful monarch by both the Parsig and Pahlav factions, Yazdegerd did not seem to have held sway over all of his empire. 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. The Pahlav, who were mainly based in the northern portion of the empire, refused to mint coins of him. The Arab invasion of the Sasanian Empire Throughout this period the great expansion of Arab-Muslim armies had slowly been penetrating the south-western frontiers under Caliph Umar ibn al-Khattāb. The Persians had repeatedly blocked this advance and in 634 the Caliph's army suffered a seemingly decisive defeat at the Battle of the Bridge. The Sasanian general Bahman Jaduya, though, was ordered back to Ctesiphon by Rostam in order to put down a revolt in his own capital city. Caliph Umar's forces retreated, only to launch a successful assault three years later. In 636, Yazdegerd III ordered Rostam Farrokhzad to subdue