The San Pedro Cactus is the common name for hallucinogenic members of the Trichocereus genus. It's a columnar cactus that can reach 20 feet in height and contains mescaline. Huachuma is one of Peru's most sacred plants, alongside tobacco and coca.

Other psychotropic alkaloids have also been discovered in the San Pedro Cactus. The skin, which can be dried, peeled, and ground into a powder, includes the highest concentration of mescaline. San Pedro cactus is also known as Huachuma. 

The San Pedro Cactus has been used in Peru for more than 4000 years. Archeological evidence was discovered near the Cordillera Blanca Mountain range in Peru, once home to the Chavin civilization. This demonstrates the long-term use of huachuma in Peru. The Chavin was Peru's first developed civilization, and they had a significant influence on all subsequent civilizations in the region, including the Inca.

San Pedro has been ingested by Andean cultures for thousands of years for 

• healing, 
• religious divination,
• and spiritual awakenings. 

 Chavin Lore

According to the earliest evidence, humans first used it in approximately 1300 BC. A stone carving depicting a supernatural creature holding San Pedro Cactus can be found in a temple dating to the ancient Chavin culture in Northern Peru. This would be a shaky but intriguing link to the Chavin people who ate San Pedro. The discovery of 3000-year-old San Pedro cigars at the exact location provides ample evidence for scientists to prove its use.

Another example is a stone engraving depicting a "huachumero" (a shaman who works with huachuma) holding a San Pedro Cactus. The carving, according to archeologists, dates from 1500 B.C. or earlier. Huachuma is still used in northern Chile, Ecuador, and Bolivia, where many still follow the traditional Chavn customs. Many religious artworks of figures holding the San Pedro cactus were produced by the Chavin tribe, making it the oldest known hallucinogenic medicine. 

Another artwork, of an owl-faced woman holding a cactus, dates from 1200 AD and is carved on a ceramic pitcher from the Chim culture. It's believed that the owl is a patron spirit and guardian of herbalists and shamans. 

Spanish Lore

During the Spanish Invasion, when Roman Catholic authorities claimed South America as their own, they attempted to prohibit the native people's use of huachuma. This endeavor only served to encourage individuals to keep their ceremonies private. This explains why huachuma rites begin after midnight. Huachuma became known as "San Pedro" (Saint Peter) after the Spanish occupation. St. Peter is the Christian saint who "holds the keys to heaven." According to legend, using San Pedro can assist the person in reaching heaven while still on Earth, or Sand Pedro is the key to heaven.