Asalha Puja, also known as Dhamma Day, is one of the most significant festivals in the Buddhist calendar. It is celebrated on the full moon day of the eighth lunar month, which usually falls in July. The month of Asalha, according to the ancient Indian calendar, marks the beginning of the monsoon season. During this time, the Buddha and his disciples would suspend their travels, a tradition that continues today in monasteries through a three-month retreat known as Vassa. This retreat begins on Asalha Puja and concludes on Pavarana Day.