Bronzes mark the beginning of civilization in ancient China. They epitomize the nobles' reverence for rites. Bronzes are called "ritual vessels", as they served as ceremonial offerings for gods or ancestors, official gifts for a mutual exchange, or utensils at banquets. Nobilities, according to their ranks, were entitled to possess bronzes of various types and sizes. Bronzes were an indispensable tool to consolidate the reign. They were a symbol of power.

Looking back into the history, bronzes of the Xia, Shang and Zhou dynasties were admired for their myriad forms, intricate patterns, and superb casting techniques. They reflect the breadth and profundity of Chinese culture and the marvellous creativity of ancient Chinese. In the Qin and Han dynasties, the popularity of bronzes declined. Later in the Song, Yuan, Ming, and Qing dynasties, the bronze art reappeared with archaism. Bronzes from the remote and border areas were distinctive in shape and style. These precious artifacts help to understand the cultural profile and mutual integration of ancient ethnic minorities in China. They have also witnessed the development of plural and integrated pattern of Chinese civilization.

(Xia, 21^st – 16^th century BCE)

Around the 21^st century BCE, China entered the Bronze Age. Small bronzes were found in the Taosi site in Shanxi province and the Shimao site in Shaanxi province. In the Erlitou site in Yanshi, Henan province, archaeologists discovered bronze containers, musical instruments, weapons, tools, and ornaments, as well as sites of bronze casting foundries. The Erlitou Culture in the late period (18^th-16^th century BCE) of the Xia dynasty was comparatively a mature bronze culture in China.

In this period, the bronze vessels were evenly shaped with thin wall and decorated with simple designs. The piece-mold casting became sophisticated. Patterns of animal mask and turquoise inlays appeared. Bronzes possessed ritual value, marking the beginning of a civilized society in China.

(Early and Middle Shang, 16^th – 13^th century BCE)

This was a critical period for the evolvement of Chinese bronze art. The system of ritual vessels was established chiefly based on the use of wine vessels in combination. Bronze weapons increased in variety. The animal-mask motif decorated most of the bronzes in a dense and complex composition. The patterns were executed with bold, deeply cut linear elements. Inscriptions with one character began to appear. The application of separate casting became more proficient. Techniques of making and combining molds made considerable progress. Bronzes from this time have been unearthed along the Yellow and Yangtze rivers. The period laid the foundation for the prosperity of ancient Chinese bronze art.

(Late Shang and Early Western Zhou, 13^th – 11^th century BCE)

The period from the late Shang to the early Western Zhou witnessed the zenith of Chinese bronze art. In the Shang dynasty, the system of ritual vessels with an emphasis on drinking vessels reached perfection. Wine vessels achieved a rich variety and an appreciable quantity.

Animal motifs such as animal mask, dragon, and phoenix were unprecedentedly sophisticated. These imposing and vigorous patterns were delicately crafted in a mixed manner of relief, high relief and intaglio. Most bronzes bear inscriptions that identify families and ancestors. In the late Shang period, inscriptions recording events emerged. In the early Zhou, some ritual practices of the Shang dynasty remained, but the ritual system shifted the emphasis from drinks to food. In this period, inscriptions on bronzes grew longer.

(Middle Western Zhou, Late Western Zhou, Early Spring and Autumn, the end of 11^th – the first half of 7^th century BCE)

The period marked a turning point in the ancient Chinese bronze art. The system of food vessels as dominant ritual vessels became fully mature. Ensembles of ding vessels, zhong (chime bells) and water vessels appeared. This trend indicated significant changes in ritual practices and social norms. Animal mask patterns gave way to those stylized animal motifs crafted in a simple and spontaneous style. Inscriptions were increasingly common on bronzes. Many important vessels bear long inscriptions. In the early Spring and Autumn period, the bronze forms and motifs inherited from those in the mid-to-late Western Zhou.

The vassal states established their own bronze casting industries, but their production qualities varied from state to state.

(Middle Spring and Autumn Period, Late Spring and Autumn Period, Warring States Period, the first half of 7^th century – 221 BCE)

From the middle Spring and Autumn period to the Warring States period, the Chinese bronze art enjoyed a second flowering. The bronzes made in vassal states developed towards maturity with distinctive regional characteristics. Regional bronzes complemented each other, including those made in states of Qin, Jin, Qi, Lu, Yan in the Central Plains, the State of Chu in the south, states of Wu and Yue in the southeast, Ba and Shu in the southwest and the northern steppe. Bronzes tended to be more practical. The ritual function declined. Intricate patterns and innovative designs appeared more than before.

Dragon-themed motifs were crafted in a detailed and dense manner. Scenes of human activities emerged as the main motif for the first time. Characters in inscriptions focused on aesthetic appeal. The methods of lost-wax and pattern blocks were applied in the casting process. Delicate inlays showcased superb craftsmanship in this period.

(Qin till the Five Dynasties, 221 BCE – 961 BCE)

This period saw the decline and fusion of Chinese bronze art. During the Qin and Han dynasties (221 BCE-220 CE), the ritual significance of bronzes faded. Simple craftsmanship and plain aesthetics went popular. Bronzes were more functional. During the Western Han (206 BCE-8 CE), the wide use of iron tools made it easier to incise patterns on bronzes. It became popular to decorate bronzes with incisions. Techniques such as gold and silver inlays, gilding, and painted designs exuded immense charm. At the same time, in the south western region, the bronzes of the Dian culture reached their peak. During the Wei, Jin, Northern and Southern dynasties (220-589), the process of cultural integration among various ethnic groups accelerated. The traditional cultural values of bronzes changed greatly. In the Sui (581-618) and Tang (618-907) dynasties, frequent cultural exchanges between China and foreign regions introduced exotic features into daily wares.

(Northern Song till Middle Qing dynasty, 960-1840)

During the Northern Song dynasty (960-1127), the ruling class, facing political reforms, endeavoured to reshape rite system and establish a new hierarchy of rites and laws. As more bronzes from the Xia, Shang, and Zhou dynasties had been unearthed, a nostalgic sentiment grew in the imperial court and among literati, longing for the culture in the three ancient dynasties. After Emperor Huizong established rules of rites and music, new ritual significance was attached to the bronze art. In the Yuan (1271-1368), Ming (1368-1644), and Qing (1644-1911) dynasties, as the ruling class prized Neo-Confucianism proposed by Zhu Xi (1130-1200), ritual vessels cast for Confucius schools and ancestral temples followed the styles of those from the Northern Song dynasty. Such practice of ritual bronzes also impacted the entire East Asia.

Bronze is one of the earliest alloys smelted by humans. The mastery of bronze production indicates how advanced a civilization is. The earliest known bronze casting site in China is the Erlitou bronze casting foundry (17^th-16^th century BCE), located in Yanshi, Henan province. The site reflects an increasing maturity in the bronze casting techniques at that time.

During the Shang and Zhou dynasties, Chinese bronze metallurgy, including mining, smelting and casting, reached a high level of proficiency. Various compositions of copper, tin, and lead made it possible to cast bronze wares with different properties. Ancient Chinese mastered the art of casting molds of different materials and employed a combination of techniques to cast large and heavy bronzes as well as thin and intricate ones. Later, with the introduction of the burn-out and lost-wax techniques, artisans could cast bronzes in one-piece mold. The décor on bronzes became increasingly intricate.

Bronzes glittered with elaborate surface decorations such as polychrome inlays, openwork design, and gilding.

Bronze production technique was the backbone of China's Bronze Age. Without the technique, the rites and music system would not have been implemented in visual or physical existence, nor could the past have been learned from inscriptions. Ancient craftsmen used their amazing intelligence and skilful hands to create and foster the magnificent and splendid Chinese bronze culture.

Advanced mining and smelting of copper are the foundation for bronze casting. Ancient copper mining and smelting sites from the Shang and Zhou dynasties have been discovered in regions such as the middle and lower reaches of the Yangtze River, the middle and lower reaches of the Yellow River, and the west Liao River basin.

These findings demonstrate that our ancestors were capable of efficiently handling complex technical challenges in the processes of prospecting mines, mining, and smelting ores.

Sufficiently high temperature is absolutely crucial to smelting copper ore into copper ingots. The temperature is closely related to the structure of the furnace and the adequate flow of air in the furnace. The vertical furnace discovered at the ancient copper mining and smelting site at the Tonglü Mountain in Daye, Hubei province, is dated as far back as the Spring and Autumn period. It has a quite sophisticated structure. Its use of manpower for air-blowing helped raise the smelting temperature to produce the copper ingots with high purity.

During the Shang and Zhou dynasties, bronzes were primarily cast with clay molds. The molds were made by mixing clay with various materials. After a certain process, the molds acquired superior castability. Shang and Zhou craftsmen mastered the techniques of making clay molds and copper smelting. They also obtained sufficient knowledge of the alloy properties of bronze and knew of making bronzes by selecting and combining proper techniques, such as one-piece casting, separate casting and cast-on, and welding. For objects in high demand, such as tools, chariots, and daily utensils, craftsmen would use the stack casting technique and metal molds to improve production efficiency.

In the burn-out casting, the model is made from combustible materials. A clay mixture is applied to the model exterior to make the mold. The mold and model are then baked under high temperature. In this process, the mold will get hardened while the model is burned away, leaving a cavity where the bronze melt is poured into. The final product will be identical with the model which has been burned. In the mid-Shang dynasty, craftsmen used this technique to make handles for some bronzes.

In lost-wax casting, the wax model fashioned in the shape of the desired object will be coated with a clay mixture.

During firing, the wax melts away, leaving behind a solid clay mold. This technique allows for producing more easily complex three-dimensional and delicate openwork designs, signifying a giant leap in bronze casting technology. The earliest surviving bronzes made through this method date back to the Eastern Zhou dynasty.

Ancient Chinese bronzes are primarily composed of three metal elements: copper, tin, and lead. Different proportions of the three metals produce bronze alloys with different properties. Ancient craftsmen gained and applied the knowledge. The book Kaogong Ji (Artificers' Record) compiled in the Eastern Zhou dynasty records the compositions and smelting temperature of bronze alloy. It is the earliest known literature on smelting of alloys in the world.

Metal composite technology produces metal objects with different alloys through the twice-casting technique, to make full use of the properties of different metals. In the Spring and Autumn period, the Iron smelting technique improved the casting of bronze and iron together in one single piece.

The original colour of bronzes can be either golden or polychrome. Bronzes can be decorated by adopting various techniques including turquoise inlaying, red copper inlaying, gold and silver inlaying, gilding, painting, gold and silver plating, and mother-of-pearl inlay. The colour of bronze itself can change from red to yellow and then to a whiter shade with an increasing proportion of tin. During the Eastern Zhou, craftsmen used this knowledge to create intricate lozenge-shaped or bright spot-patterned decorations. The surface treatment not only makes the bronzes more splendid but also enhances their performance. The invention of “mirror polishing medicines” in no later than the Western Han dynasty, for example, largely helped to brighten, whiten and protect the surfaces of bronze mirrors from erosion.