As we all know Dashavatara is an important ingredient of our Hindu mythology. Lord Vishnu, one of the principal Hindu Gods, descends on the earth in different incarnations (Avatars) to save the world from the ill effects of bad people. There are ten such occasions in our epics although the tenth one is yet to take place. That is the Kalki Avatar which will end the Kaliyuga.

The first seven Avatars are Meena, Kurma, Varaaha, Narasimha, Vamana, Parashurama and Rama. There is no ambiguity about these in literature. There is no ambiguity about the tenth (kalki) either. But there are different versions concerning the eighth and the ninth ones. According to Wikipedia there are five different narratives. They are KRISHNA-BUDDHA, BALARAMA-KRISHNA, BALARAMA-BUDDHA, KRISHNA-VITHOBA and BALARAMA-JAGANNATHA.

The fourth and the fifth variants above can be disregarded as they are parts of regional folklore. We are left with three candidates for two slots – Krishna, Balarama and Buddha.

Balarama and Krishna are characters appearing in Mahabharata. Although Balarama has a relatively minor role in the epic, he partnered Krishna in killing their maternal uncle Kamsa. On the other hand, Buddha is a part of history. He lived in India during the seventh century BCE and was the founder of Buddhism. It is also a fact that our epics predate Buddha’s lifetime by many centuries and it is unlikely that authors would have foreseen the emergence of Buddha.

All things considered, it can be conjectured that the avatars were originally BALARAMA-KRISHNA and later got modified to KRISHNA-BUDDHA. According to Wikipedia, the latter version is widely accepted today. There are many devotional Stotras and hymns which adhere to this narrative. For example, the well-known Ashtapadi (Palaya Pryodhi Jale) has the following lines

nindasi yajña-vidheḥ ahaha! śruti-jātam
sadaya-hṛdaya darśita-paśu-ghātam |
keśava dhṛta-buddha-śarīra
jaya jagadīśa hare ||8||

Another popular Dahavatara stotra (Vedodhara Vichaara mate…) contains these lines (meaning)

He left the town and his virtuous wife for the sake of killing the sorrow of humans,
He won over the cities by his form of search,
My salutations the greatly wise one who has pure wisdom,
And I request him to look after me who am a devotee of Vishnu.

The question to be probed then is about the appearance of Buddha in the Hindu mythology. When and how did this happen?

There are also two associated questions.

Why did Buddha, an avatar of Lord Vishnu, found a new religion or propose a new way of life?

The second question concerns the recognition by the Hindu devotees. Of the ten avatars, Hindus worship mostly three. They are Rama, Krishna and Narasimha. The most notable among the non-worshipped avatars is that of Buddha. There are no Hindu temples featuring Ramanvami and Janmashtami are popular Hindu festivals. But Buddha Poornima is not.