Tatung in Hakka is a person who is possessed by the spirit of a god or ancestor. Where the person’s body or body is used as a means of communication or an intermediary between the ancestral spirits or gods. By using certain Mantra and Mudras the divine spirit is summoned to the altar and then enters the person’s body.
Gods or ancestral spirits are usually called with certain interests, for example to carry out medical activities or ask for advice deemed necessary. Most of the divine spirits were summoned for activities related to the beliefs of Taoism, including medicine, exorcism, Hu making, and so on. After the activity is done, the spirit will leave the person’s body.
In China, the tatung tradition is extinct, while areas in Indonesia that still have this tradition are West Kalimantan and Bangka Belitung.
Source : wikipedia