An entheogen is a psychoactive substance that induces alterations in perception, mood, consciousness, cognition, or behavior for the purposes of engendering spiritual development or otherwise in sacred contexts.
Naturally occurring entheogens such as psilocybin and DMT (in the preparation ayahuasca), were, for the most part, discovered and used by older cultures, as part of their spiritual and religious life, as plants and agents that were respected, or in some cases revered for generations and may be a tradition that predates all modern religions as a sort of proto-religious rite.
One of the most widely used entheogens is cannabis. The entheogenic use of cannabis has been documented in regions such as China, Europe, and India, in some cases for thousands of years. It has also appeared as a part of religions and cultures such as the Rastafari movement, the Sadhus of Hinduism, the Scythians, Sufi Islam, and others.