This type of crackle-glaze vase was produced in the vicinity of Hangzhou to the order of the Southern Song court from the mid-12th century, an era of great cultural achievement. Suitably for an official (guan) ware of the Southern Song court, it shows both nobility of form that hints at the Bronze Age style and a subtle and rich glaze. The glaze is of an indefinable creamy-to-pearl grey, applied in many layers, and developing a bold pattern of dark-stained crackle.

Bibliographic References: Kerr, Rose. Song dynasty ceramics. London:V&A Publications, 2004, plate 88. 

Masterpiece entry 
This jar is a fine example of Guan ware (meaning 'official ware'), the distinguishing feature of which is its crackled glaze. Crackles occur when the glaze shrinks more than the clay body beneath, the disparity between the two rates of contraction causing the glaze to craze. In this particular case the crackles were deliberately created, as Chinese connoisseurs considered them a pleasing feature. Modern scientists have analysed the Guan glaze and concluded that Chinese potters caused the crazing by reducing the silica content in the glaze mixture.

As its name implies, Guan ware was fired in kilns that were under direct control of state officials. In 1126 the Song dynasty capital, Kaifeng, was captured by a fierce nomadic minority, the Nüzhen. The Song court fled to regions south of the Yangzi River and eventually set up a new capital in Hangzhou. Supplies of ceramics from northern kilns such as, Ding and Yaozhou, were no longer available. As a result, two kilns were established by imperial command, one called 'Xiuneisi' (literally 'Palace Maintenance Office') and the other 'Jiaotanxi' (literally 'Beneath the Suburb Altar'), both to produce ceramics exclusively for court use. 
Liefkes, Reino and Hilary Young (eds.) Masterpieces of World Ceramics in the Victoria and Albert Museum. London: V&A Publishing, 2008, pp. 44-45.