This event occurred early in the Buddha's teaching life.
After the first Rains Retreat (Vassa) at the Deer Park at Sarnath, the Buddha went to Rajagaha city where 1250 Arahats,(Enlightened saints) who were the Buddha's disciples, without prior appointment, returned from their wanderings to pay respect to the Buddha. The assembly is called the Fourfold Assembly because it consisted of four factors: (1) All 1250 were Arahats; (2) All of them were ordained by the Buddha himself; (3) They assembled by themselves without any prior call; (4) It was the full moon day of Magha month (March).
People go to the beach or river bank with jars or buckets of water and splash each other.
When everyone is happily wet they are usually entertained by boat races on the river.
People bring bowls made of leaves (which contain flowers) candles and incense sticks, and float them in the water. The traditional practice of Loy Krathong was meant to pay homage to the holy footprint of the Buddha on the beach of the Namada River in India.People clean their houses and wash their clothes and enjoy sprinkling perfumed water on the monks, novices and other people for at least two or three days.They gather around the riverbank, carrying fishes in jars to put into the water, for April is so hot in Thailand that the ponds dry out and the fish would die if not rescued.There are two aspects to take into consideration regarding Buddhist festivals: Most Buddhists, with the exception of the Japanese, use the Lunar Calendar and the dates of Buddhist festivals vary from country to country and between Buddhist traditions.
There are so many Buddhist festivals, here are some of the more important ones: In Theravadin countries, Thailand, Burma, Sri Lanka, Cambodia and Lao, the new year is celebrated for three days from the first full moon day in April.(Fourfold Assembly or "Sangha Day") Magha Puja Day takes places on the full moon day of the third lunar month (March).