International Social Science Journal (Chinese Edition)

No.3, 2020

The “South China Sea” trade goods recorded in the Southern Song’s mathematical books: centered on the chapter “To Count the Costs of Goods” in Mathematical Treatise in Nine Chapters

(Abstract)

DOHI, Yoko

As evidence of the growing foreign trade in the Song Dynasties, Qin Jiushao (1208-1268), a mathematician in the Southern Song Dynasty, wrote a book titled Mathematical Treatise in Nine Chapters (shushu jiuzhang). There are two questions on foreign trade, which had never been seen in previous mathematical books. One is to calculate the prices of Lignum Aquilariae Resinatum, frankincense and Eretmochelys imbricata. Second is about how to divide the profit from an overseas trade with joint investments. The article focuses on the second, and discusses in detail on the methods through which trade with joint investments was carried out based on the numbers recorded in the book. Of course, there are questions to be answered: 1) the profit from Lignum Aquilariae Resinatum is too little, are there any errors in the record of the unit? 2) is the large amount of peppers related to the high demand at that time? Marco Polo once marveled at the huge amount of peppers consumed in Hangzhou. Maybe, it is true that peppers began to be used in great amount in the dynasty.