According to “Comprehensive Records on Natural Science,” there are three types of Nanmu Wood: first, the aromatic Nanmu, which is slightly purple and fragrant with a beautiful pattern; second, the Nanmu with gold threads (another name for `Zhen Nan’ and `Purple Nan’), which has golden threads in the grain and is the best kind of Nanmu, and what’s more precious is that some Nanmu wood naturally forms patterns of landscapes, people, and flowers; third is water Nanmu, which is softer and often used in furniture making. Ancient emperors’ dragon thrones were made of high-quality Nanmu, which was also a special material for constructing royal palaces, mausoleums, and gardens since the Qing dynasty, and it became rare then. In the late Ming Dynasty, Xie Zaihang’s “Five Miscellaneous Morsels” mentioned that Nanmu grows in the mountains and valleys of Chu and Shu, with trees hundreds of meters tall half-buried in sand and soil. Therefore, they are cut to make coffins and called ‘sand boards.’ The finest boards have grain when opened and are as hard as iron and stone. To test them, they would be made into boxes to store raw meat for several nights, and the color would not change.