The cobalt blue glaze on this dragon flask exemplifies two characteristics common in underglaze blue wares of the first decade of the 15th century, namely, the Yongle and Xuande periods. The blue has great depth and intensity, and is characterized by what is called "heaped and piled" effects in places of purposely increased concentrations of pigment. The glaze surface tends to be uneven, like an "orange peel" to the touch, because of the coarse grinding of the glaze materials.Both the Yongle (AD 1403 - 24) and Xuande (AD 1426 - 35) emperors sponsored important maritime trade and diplomatic missions to the Middle East. The form of this flask was not originally Chinese but inspired by a Middle Eastern shape, possibly an enamelled glass vessel. During both the Yongle and Xuande emperors' reigns, flasks in this large, heavy, bulbous form with variations to the decoration were made at the imperial kilns at Zhushan in Jingdezhen. A similar item is now on permanent display at the ceramics gallery of the Percival David Foundation in the British Museum.