text: Joseph Needham, the eminent historian of science and technology, divided Chinese alchemy into the "golden age" (400-800) from the end of the Jin to late Tang dynasty and the "silver age" (800-1300) from late Tang to the end of the Song dynasty. Furthermore, Fabrizio Pregadio uses "golden age" in specific reference to the Tang period.
  The extant Chinese alchemical literature comprises about 100 sources preserved in the Daoist Canon. These texts show that while early  was mainly concerned with the performance of ceremonies and other ritual actions addressed to gods and demons, a shift occurred around the 6th or 7th century to the later tradition that used alchemical symbolism to represent the origins and functioning of the cosmos, which played a crucial role in the development of .