The Potao Apui, or King of Fire, is the foremost of the Jarai sacral masters (potao), a hereditary officiant traditionally drawn from the Siu clan whose ritual labour is held to secure rain, agricultural fertility, and cosmic equilibrium for the highland communities of the Ayun and Apa river basins. He is not a territorial ruler but a master of the yang, a mediator whose person is hedged by numerous prohibitions. His central charge is the guardianship of a sacred sabre, an object of Cham association whose latent power he alone may tend. Vietnamese and Cambodian courts long treated the Fire King and the Water King as sovereigns of the interior, exchanging periodic gifts recorded from the eighteenth century onward. Jacques Dournes, whose Potao (1977) remains the fullest study, read the institution as a Jarai theory of power in which authority is deliberately held apart from coercion. The consecrated line is generally held to have lapsed with the death of the last incumbent in the late twentieth century.