Cloisonné is a technique of decorative enameling. Sections of the object to be enameled are defined with wires and areas of color are laid down. The term comes from the French word cloisonner, to partition. Examples of Chinese cloisonné date as far back as the 1200s, I think; perhaps it originated in West Asia and spread along the Silk Road.
The development of cloisonné as a major art form in Japan is traditionally attributed to a daimyo artist named Kaji Tsunekichi of Nagoya in Owari Province (modern Aichi Prefecture), who deconstructed a Chinese example to analyze the technique. In part to satisfy Western demand after the opening of Japan, schools of cloisonné artists were producing large numbers of very fine examples by the end of the century. The period from 1880 to 1910 is sometimes called the golden age of Japanese cloisonné.
Shown is a lidded copper-body cloisonné enamel vase with a dragon motif from the collection of the V&A. Probably from Nagoya, it is dated to 1880-1890 (museum no. M.205-1917).