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) and weighed 82 Chinese
jin. This weight is estimated either at or , as a Han dynasty jin was , while the jin used in the Ming dynasty—during which the Romance of the Three Kingdoms was written—was . However, while the famous novel
Romance of the Three Kingdoms by Luo Guanzhong describes him as wielding the guandao, this description may have been an anachronistic one intended to make the character seem more imposing: historically speaking there was no evidence to show that Guan Yu used the weapon that is thus attributed to him, and indeed there is no indication of the existence of what is now known as the guandao prior to the 11th century, when it was first illustrated in the military manual
Wujing Zongyao. The guandao, therefore, possibly did not even exist during Guan Yu's era, meaning that it could be somewhat of a pop culture-derived misnomer. Furthermore, the scholar
Tao Hongjing (456–536 AD) recorded in the
Gujin Daojianlu (古今刀劍錄, "A Catalogue of Ancient and Modern Sabers and Rapiers") that Guan Yu forged a pair of sabres using iron ore he harvested from Wudushan mountain (武都山) himself, which may have inspired the story that Guan Yu invented his weapon. However, this would also indicate that he did not use a guandao or even anything resembling a guandao, since the pole-mounted or long-handled dao weapons such as the
pudao or
dadao were all wielded with two hands and so would not have been made or used in a pair. While some historians still contend that the guandao was simply an uncommon weapon prior to the
Tang dynasty and was thus not illustrated before then, historical evidence leans towards the attribution being an instance of creative license. By the time of the Qing dynasty the guandao, for the most part, was not actually intended for field use but was instead used as a tool to test the strength of those who wished to become military officers: weapons of various weights were made, and the test comprised simply performing various required maneuvers using such weapons. During the
Qing dynasty some extraordinarily heavy versions of guandao were made for this purpose: a candidate had to be able to wield a weapon weighing 80, 100, or 120 jin (, , or , using the modern value for 1 jin = approximately ), with weapons of each weight being successively higher grades in the exam, the passage of which led to appointment as military officers of various ranks based on the grade. The heaviest known "testing guandao", which resides in a museum at
Shanhaiguan, weighs . While the examples are taken from the Qing dynasty and therefore may have been influenced by the book (which was written in the Ming dynasty), military officer tests (which began in the Tang dynasty) have always involved lifting heavy stones of standardized weight and maneuvering them about, possibly contributing to the writer's decision to assign an unusual weight to Guan Yu's weapon. The weapon was also widely adopted by martial artists for the purposes of training and for demonstrating their strength, perhaps also to train specifically for the military officers' tests. Where it was used, it was largely used by infantry. In the Qing dynasty, it was used by the all Han
Green Standard Army. Apart from that, the lack of standardization of the antique examples that survive to today seems to indicate that at least from the 19th century onwards it was popular in the civilian martial arts realm as well. The modern guandao as adopted by martial artists today usually weighs between , and is typically composed of a wood shaft of about in length, a short blade of about on one end, and a mace head on the other (which serves mostly as a counterweight to the blade but can also be used for striking), the whole assembly rarely exceeding in total length. The greatly reduced weight and length reflect its nature as a more practical form for martial artists. ==Combat uses==