Indologists distinguish three stages in the formation of Hinduism: Vedism, Brahmanism and Hinduism itself. Beliefs and practices of Hinduism in the pre-classical period (XVI-VI centuries BC) were based on the Vedas – a collection of ancient scriptures in Sanskrit, and therefore are called “historical Vedic religion” or “Vedism”. The Vedas are mainly devoted to the worship of various devas (gods) such as Indra, Varuna and Agni, and they also contain a description of the Soma ritual. The main religious practice of the Vedic religion was performing fire sacrifices called yajna and chanting Vedic mantras.