During the mid and late Tang Dynasty (618-907), white porcelain began being produced in northern China and celadon in southern China, the latter of which is mostly represented by Yue Kilns in Zhejiang.

A "secret-color porcelain" box made during the Tang Dynasty is excavated near Shanglin Lake in Cixi, Zhejiang province. [Photo/ thehour.cn]

Yue Kilns have mainly been found in the modern cities of Shaoxing and Ningbo in Zhejiang. Yue Kilns reached their peak during the late Tang Dynasty and early Song Dynasty (960-1279) and were used by the royal courts until the mid-Song Dynasty. In particular, "secret-color porcelain" made in these kilns is regarded as possibly the highest-quality celadon from the Tang Dynasty on.