Blue-and-White Jars of the Yuan Period Chinese ceramics had long been in demand outside of China, and an innovation of the Mongol period — decorating white porcelain with underglaze designs in blue — proved especially popular. Persia imported large quantities of Chinese blue-and-white ceramics, and Korean, Japanese, and Vietnamese potters took up versions of the style themselves. (© The Trustees of the British Museum/Art Resource, NY)