The 24 forms of Vishnu seem to have been conceived in the Mahabharatha. His roopa and forms are first mentioned in Agni Purana, the Rūpamaṇḍana and the Aparājitapṛcchā. Apart from these they are also mentioned in Vaishnava puranas such as Bhagavata Purana and Vishnu Purana. The Kesava namas were thus well established during the ancient period of Hinduism.