The Kabbalah - top texts the Sefer Yetzirah and the Zohar -- is based on an oral tradition too, funnily enough.
It originated and is associated with the Jewish religion and some claim that non-Jewish people are not capable of understanding its doctrines, which include neo-Platonic doctrines and mystical speculations, based on 10 "emanations" or sephiroth.
Nevertheless, it has had many non-Jewish adherents including Renaissance figures, and now, Madge and Britters.
According to SF Gate, Britney was spotted wearing a so-called "Kabbalah" string bracelet after she left a rehearsal for the MTV VMA Awards.