Māgha Pūjā / Meak Bochea Day
Māgha Pūjā (in Cambodia Meak Bochea) is the an important festival celebrated on the full moon day of the third lunar month in Cambodia, Laos, Thailand, Sri Lanka and on the full moon day of Tabaung in Myanmar.
It celebrates a gathering that was held between the Buddha and 1,250 of his first disciples, which, according to tradition, preceded the custom of periodic recitation of discipline by monks. On the day, Buddhists celebrate the creation of an ideal and exemplary community, which is why it is sometimes called Saṅgha Day, the Saṅgha referring to the Buddhist community, and for some Buddhist schools this is specifically the monastic community.
In Thailand, the Pāli term Māgha-pūraṇamī is also used for the celebration, meaning ‘to honor on the full moon of the third lunar month’ , and some refer to it as Buddhist All Saints Day.
Although celebrated in earlier times, Māgha Pūjā in some Southeast Asian communities- mostly in Northeastern Thailand, the festival day only became widely popular in the modern period, when it was instituted in Thailand by King Rama IV (Mongkut The Great) in the mid-19th century. From Thailand, it spread to other South and Southeast Asian countries.
Buddhists go to the temple to perform merit-making activities, such as alms giving, meditation and listening to teachings.
It is a pubic holiday in Thailand, and was previously one in Cambodia, until recent changes were made in 2020. WIKIPEDIA