仏滅紀元
In South Asian and Southeast Asian countries as well as Mongolia, Buddha's birthday is celebrated on the full moon day of the Vaisakha month of the Buddhist calendar and the Hindu calendar, which usually falls in April or May of the Western Gregorian calendar. The festival is known as Buddha Purnima, as Purnima means full moon day in Sanskrit. It is also called Buddha Jayanti, with Jayanti meaning birthday in Sanskrit.