The ancient semi-legendary Kayani kings are the heros of Iran's national epic, the Shahnama and the holy book of the Zoroastrians, the Avesta. According to Yasnas 5 & 105 of the Avesta, Zoroaster prayed for the conversion of the Kayani King Vištaspa, who appears as a historical personage. King Vistaspa became Zoroaster's protector and patron.

Kayani is used as a title and family name by the Gakhar tribe of NW Pakistan (see also Keyani, Kiani and other spellings).

Shahnameh: The Persian Book of Kings by Abolqasem Ferdowsi, Dick Davis.

The Zend Avesta (Sacred Books of the East) by F. Max Muller

Zoroastrians: Their Religious Beliefs and Practices (Library of Religious Beliefs & Practices) by Mary Boyce