For instance, celadon ware from the Ru kiln of the Northern Song dynasty is among the most highly prized of any Chinese porcelain, but because the kiln survived for such a short period--it had barely started producing its excellent pieces when troops led by the Jin general Wu Zhu destroyed the Northern Song dynasty in 1126--only some 60-odd pieces now survive in collections worldwide.
例如北宋汝窯的青瓷，是中國瓷器的登峰造極之寶，但因為建窯時間很短，才燒出美器，金兀朮就領兵滅了北宋，因此全世界流傳的收藏不過六十餘件，而故宮就佔了廿三件。