Earliest Evidence of Cannabis Use - Migrazioni Virtual Cannabis Museum

A brief over view of some key points about cannabis.

Early Evidence of Cannabis Use

The earliest direct evidence of human consumption of cannabis as a psychoactive drug was found in 2,500-year-old tombs in the Pamir Mountains of western China. Wooden braziers containing cannabis residues with high levels of THC were discovered, indicating the cannabis was likely burned for its mind-altering effects.
Prior to this, there was only indirect evidence of cannabis use, such as cannabis seeds and pollen found at archaeological sites dating back thousands of years. However, these earlier strains of cannabis had low THC levels and were likely used more for fiber, food, and oil rather than for their psychoactive properties.

Origins and Spread of Cannabis

File:Karakoram-West Tibetan Plateau alpine steppe.jpg — Tibetan Plateau alpine steppe

Cannabis is believed to have evolved naturally about 28 million years ago on the eastern Tibetan Plateau. It then spread along ancient trade routes like the Silk Road as humans began cultivating the plant.
The earliest known use of cannabis dates back to around 8,000 BC in Taiwan, where it was used to make fabrics and shoes. Cannabis was also used as a food crop in ancient China by 4,000 BC.
Cannabis use for medicinal and religious/spiritual purposes is documented in ancient texts from China, India, Egypt, Greece and Rome dating back thousands of years.
The spread of cannabis across Eurasia is reflected in the related words used for it in many Indo-European and non-Indo-European languages[4].
Cannabis likely followed the migration of nomadic peoples and trade routes, with humans and the plant developing a mutually beneficial symbiotic relationship over millennia.

In summary, the earliest clear evidence of cannabis being used for its psychoactive effects dates back around 2,500 years in western China, but the plant has a much longer history of cultivation and use by humans going back thousands of years across Eurasia.