Cathay "Pratica della mercatura", a guide about trade in China, a country he called "Cathay", noting the size of Khanbaliq (modern Beijing) and how merchants could exchange silver for Chinese paper money that could be used to buy luxury items such as silk. Words related to Khitay are still used in many Turkic and Slavic languages to refer to China. However, its use by Turkic speakers within China, such as the Uyghurs, is considered pejorative by the Chinese authority who had tried to ban it. As European and Arab travelers started reaching the Mongol Empire, they described the Mongol-controlled Northern China
Cathay his "Book on the Administration of the State", apparently as two separate countries (presumably, referring to the Liao and Song Empires, respectively). The name's currency in the Muslim world survived the replacement of the Khitan Liao dynasty with the Jurchen Jin dynasty in the early 12th century. When describing the fall of the Jin Empire to the Mongols (1234), Persian history described the conquered country as "Khitāy" or "Djerdaj Khitāy" (i.e., "Jurchen Cathay"). The Mongols themselves, in their "Secret History" (13th century) talk of both Khitans and Kara-Khitans. In about 1340 Francesco Balducci Pegolotti, a merchant from Florence, compiled the