Among the Poya days in the year, Vesak full moon Poya day is considered as a vital day. The Vesak Poya day is the day when birth, enlightenment, and parinirvana of Gautama Buddha. The Buddhist peoples who living throughout the world celebrate this significant day following of "Amisa and Prathipaththi Pooja" Dhamma.

About 642 BC, Prince Siddhartha was born at Lumbini Sal Uyana on a of Vesak Poya day. Prince Siddhartha decided to leave out his all personal comfort, happiness and kingship to seeking for the truth of the world. On a day of Esala Full Moon Poya day Prince Siddharth left out his kingship court, beloved wife Princess Yashodhara and newly born Prince Rahula for seeking the truth of the world.

After leaving out on an Esala Poya Day, Prince Siddhartha spent in the wilderness to meditate on the truth of the world. At the end He followed the “comprising principle” and realized the noble Buddha in the shade of an ash tree in the Gaya Head of the Neranjana River. After realizing the noble Buddha, Lord Buddha dedicated himself to building a better society by uplifting the virtues of people around the world.

Gautama Buddha performed Parinirvana on the day of the Vesak full moon in the Upanthwana Sal forest in Malla Rata, Kusinara.

The last word of lord Buddha was, "Everything in the world is not eternal, those are changed. So do merits without delay".