Wikipedia
Siyâvoš (in ) , from Avestan Syâvaršan, is a major figure in Ferdowsi's epic, the Shahnameh. He was a legendary Iranian prince from the earliest days of the Iranian Empire. A handsome and desirable young man, his name literally means "the one with the black horse" or "black stallion". Ferdowsi, the author of the Book of Kings, (Shahnameh), names his horse Shabrang Behzād literally "night-coloured purebred".
As a young man well-versed in the arts of war, he is granted entry to court by his father, the Shah. However, his stepmother, Sudabeh, the Queen of Iran, develops a burning sexual desire for him. Refusing her advances, Siavash will have nothing to do with her plans for intercourse. She fakes a rape and abortion scene and blames the double calamity on Siavash who is forced to prove his innocence by riding through a colossal mountain of fire. Despite his proven innocence, the Shah eventually grows cold towards Siavash as he does not want to punish the woman he loves or anger her father, a powerful ally in the East. Siavash finds no alternative but to go into self-imposed exile in the mythical land of Turan, and seek shelter under the rule of Afrasiab, the tyrannical arch enemy of the Iranian Shah. Finally, Siavash is beheaded by Afrasiab's henchmen. His wife manages to escape to Iran, where her son becomes the next Shah, Kai Khosrow. Finally, Shah Kai Khosrow takes a terrible revenge on Afrasiab and inflicts a heavy defeat on the Turanian army.
Siavash is the symbol of innocence in Iranian literature. His defence of his own chastity, self-imposed exile, constancy in love for his wife, and ultimate execution at the hands of his adopted host have become intertwined with Iranian mythology and literature over the past millennia. In Iranian mythology, his name is also linked with the growth of plants.