Boun Souang Heua is a part of Lao tradition for many generations, but most younger generations forget as to why we celebrate the festive event, and it might be that the event of Dragon Boat Racing is internationally recognized, well known to all, and has an interesting myth and legend that surround the history of the event. As for our Boun Souang Heau, we also have our history and reasoning behind the event as well, it is held the day after Ork Punsa.
As we all knew that Buddhism is the official religion of Laos, and many religious events are more or less celebrated nationwide. One of the most notable celebrations is at the end of Lent or the Rains Retreat called Ork Punsa. Punsa is the period of three months during which the Buddhist monks are obliged to stay in the monasteries. The end of the Rains Retreat marks the occasion for the monks throughout the country to receive new robes and other necessities in an annual presentation ceremony called Thot Kathin (merit-making ceremony).
According to one of the monks at our local Wat (temple), in Laos, people would choose which Wat they want to Thot Kathin, the temple then place a Kathin flag as an announcement that the Kathin event is to follow. Assuming if there were no flag in front of Wat, then the villagers would join in to Thot Kathin called Kathin Samakee.