Historical Vedic religion the central ideas and theosophy in the Vedas, and synergistically integrated new ideas. Of the major traditions that emerged from Brahmanism are the six "darshanas", particular the Vedanta, Samkhya and Yoga schools of Hinduism. Vedic religion was followed by Upanishads which gradually evolved into Vedanta, which is regarded by some as the primary institution of Hinduism. Vedanta considers itself "the purpose or goal [end] of the Vedas." There are some conservative schools which continue portions of the historical Vedic religion largely unchanged (see Śrauta, Nambudiri). Of the continuation of the Vedic tradition in a newer sense, Jeaneane D. Fowler writes
Ancient Iranian religion in the ancient period. The religious information was rather oral both in composition and transmission. The non-Iranian sources are mainly Greek. The most important Greek source is Herodotus. Some of the Greek information on ancient Iranian religion is however unreliable. This is either because it is based on outright wrong information or based on misunderstandings. The historical reconstruction of ancient Vedic literature is also an important source. The earliest religious texts of the related Indo-Aryan peoples are indispensable for reconstructing the historical development of the ancient Iranian religion. The most important of these texts in this regard is the Rigveda.