Jami' al-tawarikh
In his history work "Shajara-i Tarākima", the Khan of Khiva and historian, Abu al-Ghazi Bahadur, mentions among the 24 ancient Turkmen (Oghuz Turkic) tribes, direct descendants of Oghuz Khagan. Oghuz Khagan is a semi-legendary figure thought to be the ancient progenitor of Oghuz Turks. translates as "strong". In his extensive history work “Jami' al-tawarikh” (Collection of Chronicles), the statesman and historian of the Ilkhanate Rashid-al-Din Hamadani also says that the tribe comes from the oldest of Oghuz Khan's 24 grandchildren who were the patriarchs of the ancient Oghuz tribes, and the name "Kayı" means "powerful".