According to legend, the guandao was invented by the famous general Guan Yu during the early 3rd century AD, hence the name. It is said that he specified its form and size to be made by a smithy, and was uniquely able to wield such an imposing weapon due to his large stature and legendary strength. Guan Yu's guandao was called "Green Dragon Crescent Blade" (青龍偃月刀, Qīnglóng yǎnyuèdāo) which weighed 82 Chinese jin (estimated either at 18.263 kg or 48.38 kg—a Han Dynasty jin was 222.72 grams in the metric system, while the jin used in the Ming Dynasty—during which the Romance of the Three Kingdoms was written—was about 590 grams).