The interval between the Han and T´ang periods, from 221 to 618 A.D., is marked by a rapid succession of short-lived dynasties, an age of conflict and division, in which China was again split up into warring states. The conditions were not favourable to the steady development of the ceramic industry, and little is known of the pottery of this period. From the few references in Chinese literature, however, we infer that new kinds of pottery appeared from time to time, and it is certain that the evolution which culminated in porcelain made sensible advances. This latter fact is proved by the scientific analysis of some vases obtained by Dr. Laufer near Hsi-an Fu in Shensi. There is a similar vase in the British Museum with ovoid body strongly marked with wheel-ridges, short neck and wide cup-shaped mouth, and loop handles on the shoulders. The ware is in appearance a reddish stoneware, and the glaze which covers the upper part is translucent greenish brown with signs of crackle. Dr. Laufer's vases are in the Field Museum at Chicago, where the body and glaze have been analysed by Mr. Nicholls, the results showing that the body is composed of a kaolin-like material (probably a kind of decomposed pegmatite) and is, in fact, an incipient porcelain, lacking a sufficient grinding of the material. The glaze is composed of the same material softened with powdered limestone and coloured with iron oxide. An iron cooking stove found with these vases has an inscription indicating by its style a date in the Han dynasty or shortly after it; and the nature of the pottery, in spite of its coarse grain and dark colour, which is probably due in part to the presence of iron in the clay, seems to show that the manufacture of porcelain was not far distant. Meanwhile, there is little doubt that the Han traditions were kept alive, and the discovery of green glazed ware of Han type in the ruins of Bazaklik, in Turfan,[26] a site which from other indications appears to belong to the T´ang civilisation, shows that this type, at any rate, was long-lived. Two vases from a grave on the Black Rock Hill in Fu Chou, and now in the British Museum, which are proved to belong to a period anterior to the seventh century, seem to combine Han and T´ang characteristics. They are of dark grey stoneware with a mottled greenish brown glaze, ending considerably above the base in a wavy line, which is a common feature of T´ang wares. It is highly probable that some of the tomb pottery discussed in the next chapter belongs to the later part of this intermediate period. Indeed among the pottery figures of this class there are specimens with slender, graceful bodies and elaborate details of costume (see Plate 7) which closely resemble the stone statues of the Northern Wei and the Sui dynasties; but with our present imperfect information on the tomb finds, it will be more convenient to treat these nearly related figures as one group.