When tidings reached the royal court that Afrasiab had amassed a formidable host of one hundred thousand chosen Turanian horsemen and was marching toward the borders of Iran, the heart of King Kay Kavus grew heavy with trouble. He summoned the realm's grandees and chief Mobads, lamenting Afrasiab's unending oath-breaking and declaring his intention to lead the army in person. Yet the wise Mobads dissuaded the King, reminding him of past perils when he abandoned his throne for rash campaigns, urging him instead to choose a mighty champion to command the host.
Siyavash, whose soul was deeply burdened by the relentless intrigues of Sudabeh and the friction with his father, saw in this war a path to divine deliverance and eternal glory. Praying silently that the Almighty might free him from the shadows of the court, he stepped forward, girded his loins, and petitioned his father to grant him the supreme command. Kay Kavus rejoiced at his son's noble spirit and summoned Rostam, trusting the young prince to the heroic tutelage of the Elephant-Bodied champion. Rostam swore absolute devotion, declaring Siyavash to be the very soul within his body.
A glorious host was assembled: twelve thousand elite cavalry gathered from Pars, Pahlav, Gilan, Saruch, Koch, and Baloch, alongside twelve thousand shielded foot-soldiers, led by renowned chieftains such as Bahram and Zangah-e Shavaran, escorted by five Mobads bearing the sacred Kavian Banner. As the army prepared to march, Kavus wept bitterly upon embracing Siyavash; a dark premonition settled in their hearts that they would never behold each other's faces again.
Siyavash led the host first to Zabulistan, spending a joyful month in the hospitality of Zal, Rostam, and Zavareh, engaging in feasts and hunts. Thereafter, the prince marched through Herat, Taloqan, and Marw-Rud, maintaining strict discipline so that no civilian suffered. Upon reaching the gates of Balkh, the Turanian commanders Garsivaz and Barman were struck with terror at the approach of Siyavash and Rostam. Garsivaz dispatched a swift courier to Afrasiab, begging for immediate reinforcements.
Without delay, Siyavash launched a fierce assault. After three days of unrelenting combat, the Iranian forces shattered the Turanian lines and liberated Balkh. Garsivaz and Barman fled across the Oxus River toward Termez and Sogdia. Siyavash promptly penned a victory letter to Kay Kavus on silk scented with musk and rosewater, praising God for the triumph, detailing the capture of Balkh, and asking permission to cross the Oxus to annihilate Afrasiab's remaining forces in Sogdia.
Kay Kavus received the letter with immense pride and delight. He returned a glowing reply praising his son's valor, yet commanded Siyavash to exercise utmost caution and refrain from crossing the Oxus hastily, warning that Afrasiab was deceitful and treacherous by nature. Respecting his sovereign and father's command, Siyavash halted his advance at Balkh.
Meanwhile, Garsivaz arrived before Afrasiab, recounting with dread the boundless endurance and ruthless prowess of the Iranian warriors who fought in relentless shifts without rest. Though Afrasiab flew into a rage and banished Garsivaz from his sight, secret terror took root in the Turanian king's heart as he retired to his bed full of foreboding.