That the hemp plant (Cannabis sativa) is used as food initially surprises and confuses most people. The public information system has largely restricted knowledge of hemp to its use for obtaining marijuana (Cannabis sativa), with its leaf content of the psychoactive substance delta-9-tetrahydrocannabinol (THC), rope and cloth from the fiber of the plant, and paper from the plant stalk. Yet both the oldest Chinese agricultural treatise, the Xia Xiao Zheng, written in the 16th century BC, and other Chinese records discuss hemp as one of the major grain crops grown in ancient China.