Dao ("knife") is a category of single-edge Chinese swords primarily used for slashing and chopping (sabres), often called a broadsword in English translation because some varieties have wide blades. In China, the dao is known as one of the four major weapons, along with the Gun (staff), Qiang (spear), and the Jian (sword), and referred to as "The General of All Weapons". Dao is actually a generic word used to denote any member of a family of single-edged, broad-bladed cutting or slicing tools, but in common, everyday usage means knife. The weapon, also known as dan dao 單刀 (single knife) when just one is used, is thereby thought to be an adaptation of the kitchen knives common to Chinese cuisine. Dao also appears in the names of such polearms as the pudao and guan dao, indicating the knifelike nature of their blades.
Other variations to the basic pattern include the large bagua dao and the long handled pudao.
During the Tang Dynasty, dao were exported to both Korea and Japan, influencing the swordsmithing of both nations. The blades of Tang era dao are reminiscent of the Japanese chokuto or the popular image of the quasi-mythical ninjato.
During the Song Dynasty, one form of infantry dao was the shoudao, a chopping weapon with a clip point. While some illustrations show them as straight, the 11th century Song military encyclopedia Wujing Zongyao depicts them with curved blades - possibly an influence from the steppe tribes of Central Asia, who would conquer parts of China during the Song period. Also dating from the Song are the falchion-like dadao and the long, two-handed zhanmadao.
The Mongols invaded in the early 13th century in the process of conquering the largest land empire in history. The Yuan dynasty of the Mongols influenced China and other nations considerably, particularly in the tools and tactics of war. A favored weapon of the Mongol cavalry was the sabre: this simple, one handed, curved blade had been used by the Turkic and Tungusic tribes of Central Asia since the 8th century at least. Its effectiveness for mounted warfare and popularity among soldiers across the entirety of the Mongol empire had lasting effects. The Persian shamshir, the Indian talwar, the Afghani pulwar, the Turkish kilij, the Arabian saif, the Mamluk "scimitar", and the European sabre (adopted via Hungary's Magyar horsemen) and cutlass are perhaps descended from the Turko-Mongol curved blade.
In China, Mongol influence lasted long after the collapse of the Yuan dynasty at the hands of the Ming, continuing through both the Ming and the Qing dynasties (the latter itself founded by a steppe people, the Manchu), furthering the popularity of the dao and spawning a variety of new blades. Blades with greater curvature became popular, and these new styles are collectively referred to as pei dao. During the mid-Ming these new sabers would completely replace the jian as a military-issue weapon. The four main types of pei dao are:
Besides these four types of dao, the duan dao or "short dao" was also used, this being a compact weapon generally in the shape of a liuye dao. The dadao saw continued use, and during the Ming dynasty the large two-handed changdao and zhanmadao were used both against the cavalry of the northern steppes and the pirates of the southeast coast; these latter weapons would continue to see limited use during the Qing period. Also during the Qing there appear weapons such as the nandao, regional variants in name or shape of some of the above dao, and more obscure variants such as the "nine ringed broadsword," which were likely invented for street demonstrations and theatrical performances rather than for use as weapons.
The Chinese spear and dao (liuyedao and yanmaodao) were commonly issued to infantry due to the expense of and relatively greater amount of training required for the effective use of Chinese straight sword, or jian. Dao can often be seen depicted in period artwork worn by officers and infantry.
During the Yuan dynasty and after, some aesthetic features of Persian, Indian, and Turkish swords would appear on dao. These could include intricate carvings on the blade and "rolling pearls": small metal balls that would roll along fuller-like grooves in the blade.
Some of the blades from the Qing Dynasty lived on and even had descendants see military action in the 20th century. The dadao was used by some Chinese militia units against Japanese invaders in the Second Sino-Japanese War, as was the miao dao, a descendant of the changdao. These were used during planned ambushes on Japanese troops because the Chinese military and patriotic resistance groups often had more willing soldiers than firearms.
Most Chinese martial arts schools still train extensively with the dao, seeing it as a powerful conditioning tool and a versatile weapon, with self defense techniques transferable to similarly sized objects more commonly found in the modern world, such as canes, baseball or cricket bats, for example. There are also schools that teach double broadsword shuang dao 雙刀, forms and fencing, one Dao for each hand.
One measure of the proper length of the sword should be from the hilt in your hand and the tip of the blade at the brow and in some schools, the height of shoulder. Alternatively, the length of the sword should be from the middle of the throat along the length of the outstretched arm. There are also significantly larger versions of dao used for training in some Baguazhang and Taijiquan schools.