The thesis investigated the history of the Pu Yur – Ya Yur ritual and belief and the structure of the spirit system to perceive the changing process, roles and functions of the ritual as well as the negotiation process and new meanings for the ritual used by various local groups in the context of modern development. It is found that the ritual was the belief in ancestors’ and guardian spirits in the community. The meanings of the ritual from the past to the present have been continuous, ranging from restricting and eliminating the belief from the society to attempts to revive the ritual with new meanings and individual beliefs. Since political changes occurred and the country has been open for tourism, the ritual has been used as a tourist attraction.