Shunyapurana  is the scripture of Dharma Puja, believed to have been written by Ramai Pundit in the 13th century. There is a chapter in the Sunyapurana called 'Niranjaner Rusma' or the anger of Niranjan, in which the author describes how his Buddhist co-religionists were saved by Muslim pirs and gazis from the oppression of the Brahmins. However, from a study of the language some scholars believe that Sunyapurana was written earlier than the thirteenth century and that 'Niranjaner Rusma' is an interpolation.

The description of Dharma Puja found in the main book suggests a mingling of Buddhist nihilistic ideas and Hindu folk religion. Dharma Puja has its origin in the turbulent conditions that prevailed subsequent to the defeat of the Palas and the arrival of the Senas in Bengal, and the conflict and compromise between buddhism and Brahminism. Ramai Pundit gave this syncretism an organised and institutional shape.

Sunyapurana is a champu kavya, written in both prose and poetry. The first five chapters describe the beginning of the world. The concept of Dharma Devata Niranjan is similar to the concept of nirvana in Buddhism. The five pundits described in the text, Setai, Nilai, Kangsai, Ramai and Gonsai, are strangely similar to the five meditating Buddhas. The rest of the book, divided into forty-six chapters, describes the different rituals connected with Dharma Puja. In the chapter titled 'Devi's Manani', there is a description of animal sacrifice similar to that performed by the Hindus, but which was forbidden in Buddhism. In the last two chapters there is reference to the Nath Devata. This also seems an interpolation as Nath Dharma and Dharma Puja are different. Sunyapurana is more important as a historical source than as a literary work. [Wakil Ahmed]