The Vedas came to be divided into the Rigveda (hymns), Brahmanas (commentaries), Aranyakas (forest texts), and Upanishads (a treasury of mystical and devotional texts). The Satapatha-brahmana was considered to be the oldest Brahmana. It was a great source of mantras, or incantations.
The mythological point of view changed between the period of the Rigveda and that of the Brahmanas. The Brahmanas were concerned with ritual and its effectiveness. There was a triad of gods who were most important: Agni, Indra, and Surya. Agni’s role had increased, and the symbolism of the fire sacrifice was more explicit. In the later Brahmanas there were thirty-three devas (gods), enumerated as eight Vasus, eleven Rudras, and twelve adityas—with two gods unnamed.