Bronze Age (Period in Spring and Autumn and early Warring States, 500BC - 350BC）
During this age, Bronze sword forging skills are fully developed. Alloys contained high amounts of tin (for hardness) used on the edge of the blade and Bronze containing lower amounts of tin (for softness) on the back of the blade to promote flexibility. An anti-rust compound was used at this time. Sulphide was widely used on the Bronze blade to resist rust. Iron was firstl used to forge blade. The first book about ore-refining and metal smelting was published during this time.《Kao Gong Ji》(《考工记》) recorded the percentage of tin and the percentage of copper used in these bronze blades for the first time.
Late Warring States (350BC - 221BC)
For finer blades steel is initially used. Steel permits a blade length is longer than was possible with bronze: a two-hand sword with a one meter blade length was forged while most swords are still made by Bronze.
Qin Dynasty （221BC - 207BC）
Bronze swords are still widely used however steel allows the length of the blade to be increased: some of them beyond 90 cm. Iron and steel are more widely used to make weapons.
Early Han Dynasty （206BC - 0 AD）
The skill of forging blade with steel is more mature. The length of steel blades extends to 1.2m. Combined forging skill appears in this time, the smiths forge new and different alloys to make stronger blades. Hard materials are now used on the edge of the blade, soft materials are used on the core or back of the blade. Heat treatment skill is also improved. Sword makers learn how to remove impurities from the metal by folded forging as well as how to improve the strength of the material. These skills become the foundation for Chinese sword making over the next 2000 years. The famous long weapon, Huanshou Dao (Long Dao with a ring pommel) are designed at this time.
Middle and late Han Dynasty （0 AD - 220AD）
Bronze swords are totally replaced by steel swords. Folded forging skill is fully developed. Blade forging skill begins to be exported to Korea and Japan at this time. Fish skin (and other materials such as stingray skin) are first used on the handle of Jian , only royalty can have such luxuriously decorated swords at this time.
Three kingdom period（220 - 618）
Folded forging skill spreads more widely in Asia, during this time, more new innovations occur, such as clay tempering appear. Sword makers learn to cover the blade with special clay and carbon powder, by controlling the thickness of the clay layer to control the different properties of different parts of the blade. Hamon on the blade was generated in association with this technology. Blades having the geometry of 切刃造(Kirihadukuri)/镐造(Shinogidukuri) are initially forged. At this time, Wootz Damascus weapons are first imported from India and the middle eastern countries..
Tang Dynasty （618 - 907）
Swords from this period have obviously different characteristics from any time before. Round or square hand guards are widely used. Ring pommel swords are used less frequently. The ring pommel Dao having a long handle are used more for ceremony. Many of Tang Dao and Jian are exported to Japan. More and more smiths travel to Japanese to teach blade forging as part of cultural communication at thistime. Four main technologies are brought by Chinese smiths: A. Combined alloys technology (Honsanmai, Kobuse and so on). B: Blade geometry (切刃造(Kirihadukuri) and镐造(Shinogidukuri). C: Clay tempering. D：Folded forging skill (called “hundreds of times forged steel” (百炼钢) in China.
Song Dynasty (960-1279)
The king of Song Shenzong establishes a special department to supervise the fabrication of weapons. A professional book 《军器法式》《Jun qi fa shi》is written serves as a weapon making guide at this time. NoDachi was invented at this time to fight cavalry attacks from northern China. The NoDachi is a long-blade sword widely used after the Song Dynasty until the Qing Dynasty. The specification for the typical NoDachi includes a 90cm blade length and with a 30cm handle. At this time the Dao having a ring pommel emerges popular again. Sincethe Song Dynasty, Japanese-made swords begin to be exported to China and to be collected by the wealthy. Japanese swords at this time have thinner-but more beautiful blades and are very well made. These exquisite-looking swords prove unable to compete with the thicker Chinese Dao and Mongol swords however (most of Mongol swords are made by Chinese and Korea).
Yuan Dynasty (1279 – 1368)
With the Mongol invasion of China in the early 13th century and the formation of the Yuan dynasty, the curved steppe saber becomes a greater influence on Chinese sword designs. Sabers had been used by Turkic, Tungusic, and other steppe peoples of Central Asia since at least the 8th century CE, and this type of sword was favored among the Mongol aristocracy. Its effectiveness for mounted warfare and popularity among soldiers across the entirety of the Mongol empire had lasting effects.[wikipedia] In China, Mongol influence lasted long after the collapse of the Yuan dynasty at the hands of the Ming. Blades with greater curvature became popular, several typical Chinese Dao, such as Liuye Dao(柳叶刀) and Yanling Dao (雁翎刀)were developed based on the more curved Mongol Dao. Before this time, most Chinese swords are straight instead of curved.
Ming Dynasty (1368 – 1644)
The Ming Dynasty is a bad time for the sword smiths: income is very low and as a consequence, a career in sword making becomes a poor choice. Many swords made during this period are of low quality even the swords used to equipsoldiers. Japanese sword-making advances to where their weapons overwhelm the Chinese in battle. More and more Japanese swords are imported to China. Warfare between Japan and China provokes the Chinese military generals to action. The most famous of these, general Qi jiguang,(戚继光), publishes strict orders controlling the quality of military swords.General Guang also designs the geometry of the blade making it broader and thicker in order to deal with Japanese swords during in war (抗倭). At about the mid-Ming Dynasty, new sabers (Dao) completely replace the Jian as a military-issue weapon. The Jian becomes more a symbol of status instead of a weapon used in actual fighting.
Qing Dynasty (1644 – 1911)
The Qing’s weapon-making ability is obviously improved compared with the Ming. The king of Qianlong publishes his order to classify different weapons, including detailed instructions as to how weapons are to be carried for different levels of officers. All kinds of sword-making methods and their functional properties are recorded integrally at the behest of king of Qing Jia qing. Another very typical Chinese Dao, the Ox tail Dao (牛尾刀), is created and becomes extremely popular at this time, not only in the military, but among ordinary citizens as well. To this day, the Ox tail Dao is still a very popular Wushu weapon in China.
The spring and autumn period,Wu kingdom defeated Yue kingdom.King goujian of yue was humiliated in the Wu kingdom.He slept on brushwood and tasted gall and finally made the trust of the king of the Wu kingdom.He was put back to the Yue kingdom.On the one hand, king goujian of yue selected peerless beauty-Xi Shi to the king of the Wu kingdom to captivate him.On the other hand,he tried to make the kingdom rich and its military force efficient secretly casting sophisticated weapons.He specially selected the best craftsman Qin Zheng to caste.Qin Zheng and his son Gang Zheng spent forty-nine days forging a pair of male and female swords.Qin Zheng engraved"The sword belongs to King goujian of yue"and then said to his son"I will present the female sword to the king of Yue kingdom tomorrow morning.I am afraid that I can not come back.You take the male sword to go to Chu kingdom as soon as possible."They cried to say goodbye.
Qin Zheng presented the sword to king goujian of Yue the next day.The sword would cut clean through iron as though it were mud.In order to prevent Qin Zheng from making a sword as well as it,goujian killed him and wanted to arrest Gang Zheng.Gang Zheng was very cautious,and he buried the male sword in the mountain and then disguised as a fisherman.He fled to Chu kingdom and taught the local people the smelting craft,making the level of smelting of Chu kingdom improves rapidly.Later,Chu kingdom attacked Yue kingdom.The capital of Yue kingdom was occupied soonly.When knowing that,king goujian of Yue used the female sword to commit suicide and died.The king of Chu kingdom got the sword and gave it to a distinguished minister as areward.Later,the minister died,and the sword became his sacrificial objects.
Now,no one know where the male sword is.But, the female sword which is used by king goujian of Yue has been excavated from a tomb of Chu kingdom,It is a world famous precious cultural heritage.
The formation of Japanese pirates dates back to the Yuan Dynasty. Kublai Khan had two expedition to go to Japan. But he was beaten by the sea hurricane. The Japanese pirates invade more and more rampant after Yuan Dynast, till Ming dynasty, it has caused great chaos and fear around the south east China. So, the court delegated Jiguang Qi to resist the Japanese pirates.
Jiguang Qi found that the qualities of the Ming army's weapons in the war was inferior compared with Japanese sword. What's more, the soldiers were not familiar with the methode of fighting of Japanese pirates. Japanese pirates were good at jumping when using sword and the Japanese sword was very sharp,which caused enormous losses to the Ming army. When realising the issue, Jiguang Qi began to study how to improve the Chinese sword by learning the Japanese sword. After the efforts of Jiguang Qi and others, the long sword and the waist sword which shows Japanese-style had become one of the most important equipments of the Ming army. Later, the two kinds of sword were introduced into north border guards. As a result, the quantity of them was large. We can't rely entirely on imports from Japan. We had to made them by ourselves.
"The iron need to be forged many times, the edge material should be high carbon steel. A well-made tip is the soul of a blade.” This is recorded in a book named as "Follow the effect of the new book". Under general Qi’s guide, the Chinese army began to learn and improve the Chinese sword and later generations called this style of Chinese sword as"Qi's sword".