That a 16th-century high priest of Estakhr was named Azar Kayvan suggests that "Kayvan" was used as a name for a person in Iran as early as that time, particularly among followers of Zoroastrianism. To date "Kayvan" is a popular name among families following Zoroastrianism. "Kayvan" is distinct from the similar Persian word "Kayhan", meaning "universe", also used as a masculine given name.