Siddhartha Gautama, who founded a religion?

Buddha Purnima, also known as Vesak, is the festival that marks the birth of Prince Siddhartha Gautama, who later became Gautama Buddha, the founder of Buddhism.
This festival is observed on the full moon day (Purnima) of the month of Vaishakha (April–May). It is one of the most important festivals for Buddhists because it also commemorates his enlightenment (Nirvana) and death (Mahaparinirvana).