During which dynasty was white porcelain at its peak? （The Tang or the Song. Why?) Can you answer as detailed as possible?

Chinese porcelain production has a long history and many varieties. In addition to the noble and elegant blue and brightly colored porcelain. Elegant white porcelain is also a favorite variety, although it looks like there is no variegated pattern and bright colors, but in the simple and unadorned, it shows people that natural beauty. White porcelain generally refers to the tire is white, the surface of the transparent glaze porcelain. In the Shanghai Museum in the collection of a lot of white porcelain in the Tang Dynasty. These white porcelain production of the Tang Dynasty, the production of sophisticated, clean soil washing, few impurities, a tire is very fine, and whiteness is relatively high, after a layer of transparent glaze, reflecting the color is very white, the tea sage Lu Yu in the "Tea Classic", has respected the Tang Dynasty Xing kiln white porcelain for the best, and described its tire glaze like snow and silver as white. Late Tang Dynasty until the early Song Dynasty, Ding Kiln there is a "official" or "new official" paragraph word fine white porcelain, its basic features are: thin and lightweight, fine texture, pure white; glaze moist, glaze is milky white or white in green, in addition to the bottom foot, are full of glaze. Generally speaking, "official", "new official" paragraph Yu carved in the tire thin and delicate, exquisite production, glaze color pure white or white in the flash of green on the object, belong to the Tang, the Five Dynasties period; carved in the glaze white or white yellow or part of the slight flash of green, sometimes with the carving of the flower decorations on the object, belongs to the Northern Song dynasty early; carved in the overfiring method of firing, the mouth rim unglazed and with the carving of the flower decorations on the object, belongs to the Northern Song dynasty late. So in the Song dynasty to its heyday