Multiple factors contributed to the astonishing vitality that characterized the Chinese ceramics industry from the sixth to the twelfth century. These include heightened interchanges between the south and the north, the longstanding Chinese tradition of cross-craft exchanges in shapes and patterns, and the introduction of new forms and designs.  The latter was spurred by the expanding trade in prestige goods, particularly metal and glass from West and Central Asia, which reached China both overland on the fabled Silk Roads, and by sea. Archaeological discoveries combined with scientific examination of works of art have shown that a type of porcelain, with kaolin in the body, and vitrified glazes, was first produced in China in the second half of the sixth century, often in the shape of small cups that echo imported West and Central Asian glass forms. The development of high-fired white bodies spurred technical innovations throughout north China as well as in ceramic-producing centers in Iraq and Iran. These ultimately led to the invention of both tin-glazing and luster, technologies that underlay European majolica.