Japanese Arita rounded rectangular form porcelain platter decorated in underglaze blue with a conceptual map of Japan moulded in relief and surrounded by dense stylized fish-scale patterned waves to indicate the ocean. The various provinces, each identified in blue kanji, have incised lines separating them. The dish is marked on the slightly celadon tinted back “Tenpo period (1830-1844) made.” These dishes were made from 1830 through the Edo period (ending 1868), and this platter is consistent with the time period. 17 7/8” long x 14” wide x 1 3/4" high. The platter is large for its type, is heavily potted, and weighs 7 lbs. There are a few production imperfections in the underglaze blue waves where paint was not applied. Overglaze gilt highlights originally applied along the borders of the provinces have worn away in many areas from age and use.