The kiln site actually responsible for such refinement has so far not been located. Shao-hsing, Chechiang Province, is commonly considered their point of origin since so many jars have been unearthed from tombs in that district.…It would take until the late third century for the potters of Chechiang to reduce the amount of oxygen in their kilns to the extent necessary for the formation of the glaze color which we call celadon green.]