Today, there is general confusion regarding nomenclature. In the antiques market, “Yueh Ware” is often used very loosely to denote all ceramics with an iron-based green glaze from the Shang (1766-1045BC) up till the time of the Song dynasty (960-1279AD). However, the term “Yueh Ware” was actually coined during the Tang dynasty (618-907AD) to describe greenware originating from kilns in the administrative district of Yuehzhou in northeastern Zhejiang beginning in the Han dynasty (206BC-220AD). Due to the fact that greenware of this period was produced over much of Southern China, including the present day provinces of Jiangxi, Hunan, Fujian and even Guangdong, not to mention innumerable kilns in Zhejiang itself outside of Yuehzhou, and that we have little way of definitively attributing the kiln of origin to most of the pieces in museums and collections today, academics have generally agreed to include within the tern “Yueh Ware” all greenware manufactured in South China between the Han and Five Dynasties periods (907-960AD) as well as certain pieces from the Song dynasty. Greenware prior to the Han dynasty is termed Early Greenware or Ash-glaze ware.

Early greenware does not appear to have been made in north China as no kiln sites have been found there, and although pieces have been recovered in northern tombs, they are few in number. It is generally accepted that these vessels are imports from the south, especially the region of the old Wu-Yueh kingdoms around Zhejiang. 

During the Shang dynasty, “Dragon kilns” were developed in southern China. These were long, wood-fired kilns which ran up a slope; they were stoked from below, while the heat ran up the kiln to escape from the chimney positioned at the top. This allowed temperatures of over 1,150’C to be achieved, causing both clay body and glaze to vitrify, forming primitive porcelain and giving rise to the first high-fired glaze.

Depending on its iron content, glazes fired at above 1,150’C produce a range of colors. At an iron oxide level of 0.8%, glaze the color of windowpane glass is produced, with a tinge of green showing only where it has pooled. At levels of 1-3%, as in early greenware, a range of olives and greens are produced. Higher levels lead to brown and “black” glazes, while saturation causes silvery spots and rust-colored splashes to appear on the glaze surface due to metallic deposition.

In the earliest pieces, ash within the kiln falling on pottery being fired acted as a flux (a substance which lowers the melting point of the silica in the superficial layer of clay), causing the formation of a “natural glaze” wherever the ash settled. These vessels, speckled with olive-green on the upper surfaces, are found throughout China. A few very finely wrought Shang pieces have been discovered covered completely in a pale green glaze, thought to be due to the vitrification of an iron-containing slip on the surface of the vessel.

“Accidental” ash-glaze was soon developed by deliberately covering pieces with ash before firing. The pieces that resulted during the Western Zhou period (1045-771BC) are generally covered entirely with a rather heavy, uneven olive to dark brown glaze consisting of large running drips interspersed with very thinly glazed spaces. A common pattern consists of bands formed by incised “bowstrings” within which are comb-stippled dots. Small S-shaped spirals made by applying coils of clay are also a characteristic feature which continues into the Spring and Autumn period. Other decorative motifs include combed wavy patterns and applied animal features. Common vessel shapes include covered jars, bowls, and “Tsun” cups with flaring mouths.

By the Spring and Autumn period (772-481BC), the glaze is generally lighter and thinner, although still uneven. A pattern of bracketed circles paddle-impressed onto the surface is a common motif of this period. Sometimes these circles are interspersed with elongated S-shaped hooks.

During the Warring States period (481-221BC), there is a dramatic increase in pieces made in imitation of ritual bronzes. These are generally found in earth-mound tombs in the south belonging to the local nobility as opposed to vertical pit-tombs in the area which are associated with northern migrants, and which tend to contain actual ritual bronzes. These representations of ritual vessels are commonly covered with a pattern of spirals or square spirals in imitation of the “Picturesque style” of bronzes of the fifth century BC. Molded handles have raised spirals in the same style. Glaze on Warring States pieces also tend to be thin and pale in color, the buff colored body covered in yellowish glaze streaked with drops an dashes of darker color like a delicate “splash painting”.

Greenware production drops off and disappears during the middle to late Warring States period and does not revive until the Han dynasty. The assimilation of the state of Yueh by the state of Chu is assumed responsible for this disturbance.