The shape and decoration of this rare flask are influenced by Central Asian vessels. In China the shape seems to have evolved from the more ovoid form of the Northern Qi (550-577) examples, such as one excavated from a Northern Qi tomb in Fan Cui at Anyang, Henan, and illustrated in Zhongguo wenwu jinghua daquan - Taoci juan, Taipei, 1993, p. 114, no. 401. During the Sui dynasty, the shape broadens at the bottom and the foot is splayed, as can be seen on an example from the Royal Ontario Museum, Toronto, dated circa AD 600, and illustrated by J. Fontein and Tung Wu in Unearthing China's Past, Museum of Fine Arts Boston, 1973, p. 162, no. 77. By the Tang dynasty, the shape had become even more rounded and was still raised on a splayed foot, as seen in the example in the British Museum dated 7th or possibly 8th century, illustrated by S.J. Vainker, Chinese Pottery and Porcelain, New York, 1991, p. 63, no. 45; and another in the Victoria and Albert Museum, London, illustrated by W. Watson, Tang and Liao Ceramics, New York, 1984, p. 147, no. 126. The present flask corresponds to these Tang characteristics and the bright green glaze is also very much a Tang glaze color.