Hallucinogens are as old as civilization. Many cultures recorded eating certain plants specifically to induce visions or alter the perception of reality. Often these hallucinations were part of a religious or prophetic experience. Shamans in Siberia were known to eat the hallucinogenic mushroom Amanita muscaria . The ancient Greeks and the Vikings also used naturally occurring plant hallucinogens. Peyote, a spineless cactus native to the southwestern United States and Mexico was used by native peoples, including the Aztecs, to produce visions.