Doan Ngu is a Vietnamese word for a ceremony opening the summer solstice. In fact, Vietnam is a tropical country. Therefore, during the summer solstice, it seems that the worst fate awaits its inhabitants. Epidemics of plague, cholera, flu, etc often occur during this season. Most Vietnamese people believe that harmful spirits brought these illnesses. They think that the God of Death is especially severe during this time of year because he needs souls for his army in hell. Due to this need, he causes epidemics in order to get more soldiers.
During this celebration, people also pray for coolness. Vietnamese people erect altars in pagodas, temples or at public places for the celebration throughout the country. People make offerings to spirits, ghosts, and the also god of death. They burn votive paper, and effigies of human beings are burned in an effort to satisfy the god of death with the soldiers he needs! Normally, the ceremonies are led by Buddhist monks. In addition, many families place an amulet at their door as an added protection against epidemics.