Romans also used cannabis. In China, the psychoactive properties of cannabis are described in the Shennong Bencaojing (3rd century AD). Cannabis smoke was inhaled by Daoists, who burned it in incense burners. In the Middle East, use spread throughout the Islamic empire to North Africa. In 1545, cannabis spread to the western hemisphere where Spaniards imported it to Chile for its use as fiber. In North America, cannabis, in the form of hemp, was grown for use in rope, cloth and paper. Cannabinol (CBN) was the first compound to be isolated from cannabis extract in the late 1800s. Its structure and chemical synthesis were achieved by 1940, followed by some of the first preclinical research studies to determine the effects of individual cannabis-derived compounds in vivo. Globally, in 2013, 60,400 kilograms of cannabis were produced legally. Recreational use Cannabis is a popular recreational drug around the world, only behind alcohol, caffeine, and tobacco. In the U.S. alone, it is believed that over 100 million Americans have tried cannabis, with 25 million Americans having used it within the past year. As a drug it usually comes in the form of dried infructescences ("buds" or "marijuana"), resin (hashish), or various extracts collectively known as hash oil. During the 20th century, it became illegal in most of the world to cultivate or possess Cannabis for sale, and even sometimes for personal use. The psychoactive effects of cannabis are known to have a triphasic nature. Primary psychoactive effects include a state of relaxation, and to a lesser degree, euphoria from its main psychoactive compound, THC. Secondary psychoactive effects, such as a facility for philosophical thinking, introspection and metacognition have been reported among cases of anxiety and paranoia. Finally, the tertiary psychoactive effects of the drug cannabis, can include an increase in heart rate and hunger, believed to be caused by 11-OH-THC, a psychoactive metabolite of THC produced in the liver. Normal cognition is restored after approximately three hours for larger doses via a smoking pipe, bong or vaporizer. However, if a large amount is taken orally the effects may last much longer. After 24 hours to a few days, minuscule psychoactive effects may be felt, depending on dosage, frequency and tolerance to the drug. Various forms of the drug cannabis exist, including extracts such as hashish and hash oil which, because of appearance, are more susceptible to adulterants when left unregulated. Cannabidiol (CBD), which