The tradition of Jingtai lan (the blue of the Jingtai era) refers to the technique of creating designs on vessels using colored enamels held in place within partitions formed by metal strips or wires, the process being repeated to fill in the gaps left by shrinkage during firing. This technique reached China in the Yuan dynasty (1271–1368) from Byzantine via the Islamic world. Seventeenth-century connoisseurs claimed the cloisonne produced during the Jingtai reign (1450–1457) of the Ming dynasty to be superior, thus giving rise to the term Jingtai Lan to mean cloisonne enamel. However, authentic Jingtai period cloisonne wares remain elusive, and the emergence of a large number of cloisonne enamels bearing apocryphal Jingtai marks to meet the demands of the antique market has created an extra barrier to more precise dating. The Qianlong Emperor (r. 1735–1796), known as a great patron of the arts, attempted to collect cloisonne wares made during the Jingtai period. But rather than obsessing over the rare Jingtai wares, he was even more enthusiastic about commissioning new cloisonnes according to his own tastes from imperial craftsmen. Many unprecedented forms were thus created, leading to a golden age of cloisonne.