The Second Era continues:
THE KAYANIAN DYNASTY
Meanwhile... Kai Kavad
Afrasiyab still threatens, until Zab becomes king, and restores order. After Zab's reign, the Iranian nobles choose Kai Kavad to be their king. Kai Kavad defeats Afrasiyab, and establishes a dynasty, known as the Kayanians (all were called Kai, king).
Kavad's successor gets himself captured in an attack on Mazandaran (south of the Caspian Sea) - and it takes all Rustam's efforts to free him. Rustam has to rescue him again after an ill-advised attack on Yemen. And again after he ends up in China. The demons seize their chance, and Kavus falls into their power for a time. Hostility between Iran and Turan escalates thanks to Kavus' treatment of his son Siyavush. Accused falsely of making a move on Kavus' wife, he defects to the Turanians. He marries Afrasiyab's daughter, and becomes a favorite of the king. But his wealth and wonderful castle provokes envy among the Turanian princes, who murder him. His death causes outrage in Iran, and much criticism of Kavus. Rustam leads a revenge attack on Turan.
Kai Khusrau and his successors
Siyavush's wife is allowed to have his child, Kai Khusrau, who is being brought up in Turan. The Iranians bring him home, and make him king. With the help of Rustam and other Iranian heroes (notably Godarz and his son Gev), he invades Turan, and Gev finally captures and kills Afrasiyab. The wise and valiant Kai Khusrau weirdly disappears, after naming his successor, Luhrasp. Luhrasp reigns well for a long time. When he retires,his son Gushtasp becomes king.
While Gushtasp (Vishtaspa) is king, Zarathushtra announces his new religion. The king of Turan, Arjasp, sees this as a betrayal of the old ways, and invades Iran. Gushtasp's brother is killed in terrible fighting, but is avenged by his son Bastur, helped by Isfandiyar, son of Gushtasp. The Turanians are defeated. Gushtasp grows suspicious of his son Isfandiyar, and puts him in prison. But when Arjasp attacks again, he releases him. Isfandiyar defeats the Turanians, and kills Arjasp, in a brutal campaign during which he performs seven Rustam-like feats.
Isfandiyar v Rustam
Although he'd been promised the kingship of Iran if he beat Arjasp, Gushtasp refuses to give it to him unless he can capture the old warrior Rustam, who has apparently insulted the king. Rustam won't be captured, however, and Isfandiyar is forced to fight a series of duels. Isfandiyar shows himself Rustam's equal - until in the final contest Rustam, helped by the old bird Simurgh, delivers a mortal wound to the young contender.
Rustam has been killed by an envious brother. Bahman, son of Isfandiyar, invades Rustam's province and kills Rustam's brother and son in revenge for his father.
Kai Dara (two of them)
Humay, Bahman's daughter and wife succeeds him. She has a son, Dara, who becomes king, and whose son, also Dara, is defeated by Alexander the Great and killed in battle. Bahman had another son, Sasan, who, disgusted by his father's preference for his sister, leaves home (and will prove to be the ancestor of the Sasanian kings.).
There are two conflicting Alexanders. In Iranian tradition he's the destroyer of the Iranian empire, ending its unity by sharing it out among petty rulers. He also attacked the Zoroastrian religion, killing priests and destroying fire-temples. He stole Iranian science and philosophy, and gave it to Rum (the Greeks).
In other versions - including the Shahnameh - Alexander is a son of Dara - and thus a half brother of Dara the second. When Dara II is betrayed and killed by his own men, he begs Alexander to avenge him and marry his daughter. Alexander does so, and sets out on many adventures (including the search for the fountain of eternal life). He too divides Iran up between petty kings, and undermines the unity of Eranshahr.