Hầu Đồng (also Lên đồng) is one of the main rituals of Đạo Mẫu, and exemplifies the worship of mother goddesses in Vietnam. During these rituals, the mediums go into trances so their bodies can receive the spirits of various deities. The journey of the spirits into the bodies of the mediums is an incarnation, and the process involves the spirits briefly hovering then moving into the mediums. The mediums change their costumes to indicate which deity has entered their body.

Đạo Mẫu and its ritual, Hầu Đồng were prohibited by the French colonials and by the Ho Chi Minh Socialist regime, but has been subtly encouraged since 2000 when it was officially considered as an ancient indigenous folk religion of Vietnam, and an important cultural heritage.

Tewfic El-Sawy is the only photographer to have photographed Hầu Đồng ceremonies in such depth, and documented the maelstrom of trances, possession, spirit worship, fortune telling and clairvoyance, fashion and pageantry, sacred music and hymns, faith, belief, superstition, the supernatural, nationalism and history that constitute Vietnam’s Đạo Mẫu and its ritual; Hầu Đồng. To the best of his knowledge, there are no other photo book on these ceremonies.