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The "Biographies of Money-makers" in the *Book of Han* records: "Ten large dou of millet." Yan Shigu commented: "Large dou refers to a unit different from the standard dou used for measuring rice and millet." This indicates that during the Han Dynasty, large dou already existed but were used only for weighing bulk goods.

The *Tang Liudian* (Six Codes of Tang) stipulates: For length measurement, it is based on medium-sized millet grains from the north; the width of one millet grain constitutes one fen; ten fen make one cun; ten cun make one chi; one chi and two cun constitute a large chi; ten chi make one zhang. For volume measurement, also based on medium millet grains: one thousand two hundred millet grains fill one yue; two yue make one ge; ten ge make one sheng; ten sheng make one dou; three dou constitute a large dou; ten dou make one hu. For weight measurement, again based on medium millet grains: the weight of one hundred millet grains equals one zhu. Ying Shao stated: "Ten millet grains weigh one lei (HT); ten lei weigh one zhu; twenty-four zhu equal one liang; three liang constitute a large liang; sixteen liang make one jin." The accumulation of millet grains to establish standards of length, volume, and weight was employed for tuning bell rhythms, measuring sundial shadows, compounding herbal decoctions, and determining the specifications of crowns and hats. All internal and external government offices uniformly adopted the larger units. According to the situation in the Tang Dynasty, both ancient (smaller) and contemporary (larger) systems coexisted. The Directorate of Astronomy (Taishi), the Court of Imperial Sacrifices (Taichang), and the Imperial Medical Bureau (Taiyi) adhered to the ancient system. (This was because the Directorate of Astronomy required precise degrees, minutes, seconds, and water-clock measurements; the Court of Imperial Sacrifices needed musical pitch divisions; and the Imperial Medical Bureau required precise measurements such as daogui, fen, liang, sheng, and ge for medical purposes.) Other government departments used the contemporary system. Over time, the contemporary system became prevalent, while the ancient system fell into disuse. Du You's *Tongdian* records the local tributes from various commanderies: Shangdang Commandery offered three hundred small liang of ginseng; Gaoping Commandery offered fifty small liang of white quartz; Jiyang Commandery offered two hundred small jin of donkey-hide gelatin; thirty small jin of deer antler gelatin; Linfeng Commandery offered ten small jin of Dendrobium; Nanling Commandery offered ten small jin of Dendrobium; Tongling Commandery offered twenty small jin of Dendrobium. This shows that small jin and small liang were indeed used in tribute items, but exclusively for medicinal preparations.

Shen Kuo in his *Brush Talks* (*Bitan*) of the Song Dynasty wrote: "I received an edict to examine bell rhythms and cast armillary spheres, searching for measurement standards since the Qin and Han dynasties. Calculations showed that six dou equaled one dou, seven sheng, and nine ge in the current era; and three jin weighed equivalent to thirteen liang today." This indicates that the weights and measures of the Song Dynasty were larger than those of the Tang Dynasty.

The *History of Yuan* states that in the 20th year of Zhiyuan, the small-mouth hu of the Song Dynasty's Wensi Workshop was promulgated. It also records that when Emperor Shizu conquered Jiangnan, he ordered that rice transporters use only Song Dynasty dou and hu, because one Shi of the Song Dynasty equaled seven dou of the current era. Thus, the dou and hu of the Yuan Dynasty were larger than those of the Song Dynasty.