Cannabis seed and oil were probably used as food in China since at least 6000 BC. The earliest use of hemp in medicine goes back to the Chinese emperor Sheng Nung c. 2727 BC. It was popular as it possesses both yin and yang properties (Deitch, 2003). The cannabis was probably used as medicine or for its psychoactive properties (Russo, 2008).
There are references to marijuana in the Chinese pharmacopoeia that go back to 1500 BC (National Institute of Drug Abuse – Marijuana Research Findings – 1976, 1977). The Chinese were said to use cannabis to treat diarrhoea, dysentery, and to stimulate the appetite.
The use of cannabis in India probably goes back to the Vedic times (c. 1800 BC onwards), as mentioned in the Atharvaveda.
The Zend-Avesta, the Holy Book of the Zoroastrians (composed around 700-600 BC), has numerous references to bhang (local Indian name for recreational marijuana). It is referred to therein as the good narcotic. Sushruta Samhita mentions the use of cannabis as an anti-phlegmatic and as a cure for leprosy.
Pliny the Elder refers to using the plant both for rope-making and as an analgesic (23-79 AD). Dioscorides lists it as a medicine (c. 70 AD)
Modern research in support of traditional medicinal properties of cannabis:
The synthetic form of THC going under the trade name of Marinol was approved for medical use in May 1985 and was used to treat nausea and vomiting caused by chemotherapy. The US FDA approved this product to treat anorexia in patients with AIDS (Eddy, 2010).
According to the Indian Central Science and Industrial Research publication, Cannabis plants are used as a tonic, intoxicant, stomachic, anti-spasmodic, analgesic, narcotic, sedative, and anodyne folk medicine. Seeds and leaves are used to treat cancerous ulcers and tumours.
To know more about marijuana and other Asian herbs, you can read this book.