The many kilns around Longquan city began production in the tenth century and continued into the Ming dynasty (1368-1644). The best Longquan wares were produced in the Southern Song dynasty (1127-1279), when a thick, bluish-green glaze was used to imitate the lustre of jade, similar to the imperial wares known as Guan.Longquan green wares were made for consumption at home and abroad. In China some green wares were made in archaistic forms; that is, they looked back to earlier periods in Chinese history, copying the shapes of ancient bronzes and jades. Such archaistic pieces were prized by scholar-officials at home, and also in Japan and Korea, much of whose literary culture and philosophy derived from China. They were generally used as altar pieces in temples.This vase is in the shape of a cong, a carved ritual jade found in many Neolithic tombs (around 2500 BC), along with a circular jade shape known as a bi. Some tombs contained large quantities of such jades. The cong was an extremely difficult shape to produce in jade and, later, in ceramics.