Glazed objects appeared as early as the Western Zhou period (c 1100 - 771 BCE) in the form of ornaments, beads and screens (also known as luminous screens). By the Han dynasty (206 BCE - 20 AD) the production of various types of glazed articles became more common. Glazed tiles were first documented in the Northern and Southern dynasties (420 - 581 AD); the Chronicle of the Western Regions from the Wei Dynasty noted:

During the reign of Shizu, merchants from the country of Dayuezhi (modern day Xinjiang and the eastern part of Kazakhstan) traveling to the capital claimed they could convert rock into glazes of different colors. Rocks that were quarried in the mountains and brought to the capital to be pulverized, melted into a smoother and glossier glaze than from the rock samples the merchants had been bringing. Delighted with the result, the emperor commissioned the building of a hall to hold more than hundred guests. The completed edifice so glittered with color that all those who saw it were stunned, thinking it was the handiwork of the gods. This dazzling hall seems to be the first structure in China that used glazed terracotta. Glaze was produced in large quantities after this time and became less valued in China.

For many years, it was believed that glaze was introduced from the western regions because Dayuezhi merchants in the Wei capital made smooth and glossy glaze, but recent archeological discoveries show that glazed objects appeared as early as the Western Zhou. During the Sui (581 - 618 AD) and Tang dynasties (618 - 907 AD) important edifices using glazed tiles and bricks became increasingly common. A pivotal monograph on architecture compiled during the Song dynasty (960 - 1279 AD), Building Methods and Patterns, offers a comprehensive treatise on glaze-making techniques, including formulas for producing the basic compound. An excellent standing example is the 50-meter high purple-glazed terracotta pagoda in the Temple of the Empire's Guardian (Youguosi), known as the Iron Tower, built in Kaifeng (Henan province) in 1049.

Glazed tiles became indispensable in the design of important structures during the Yuan, Ming and Qing dynasties. The use of terracotta glaze reached its pinnacle in the construction of imperial Ming and Qing palaces. The glazed tile rooftops of many pavilions in the Forbidden City, complete with ridges and upturned corners, are decorated with handsome and bizarre animals of different sizes and shapes. Not only do these glazed animals, like the two dragons clamping the ridge beam with their jaws, project images of prowess and grandeur, but also they enhance the aesthetic appeal of the buildings.

Rooftop Creatures            The prominence and scale of a building determined the position, size, number and sequence of such ornamental creatures on a roof. A pair of dragons, the dominant rooftop decoration, bookends the extremities of the roof ridge; the body of each dragon is incised with scales, all claws are upraised and the tail rears, coiling around a sword. Although ferocious dragons became a frequently used symbol, they actually replaced the earlier use of an owl's tail. The dragon-owl beast was originally designed to avert disaster by fire; later, a legend arose that the dragon begot nine sons, one of whom was a chi. Aquatic by nature and fond of scanning the horizon, this chi, or small dragon, replaced the owl's tail as a sentinel on top of the emperor's residential hall.

A Tang text recorded:

After the Hall of Cypress Beams was flooded in the Han, a sorcerer from Yue alleged that he had seen a horned beast resembling a dragon in the water with a tail like that of an owl, which churned water into rain. For this reason the creature became mounted on rooftops to subdue fire.

The largest glazed dragons on an ancient edifice still standing in China today is the pair on the main ridge of the Hall of Supreme Harmony (Taihedian) in the Forbidden City. Composed of 13 glazed pieces, each dragon is 3.l meters high and weighs 3,650 kilograms. Although tradition dictates an odd (yang) number of tile ornaments on the upturned roof corners, the Hall of Supreme Harmony held ten mythical animals perched on each roof corner, one more than the highest permissible odd number. This marked the supremacy of the emperor.

Included in this pageant headed by a celestial being riding astride a phoenix on row 2 and moving from right to left, the other mythical beasts sit in a sequence ending with the xingshi.

Xingshi	Douniu	Xiezhi	Suanni	Yayu	Winged steed
Seahorse	Lion	Phoenix	Dragon	Celestial being

In order of rank from right to left, they are: