The Mongol conquest of the Song empire had, for the first time since the end of the Tang, reunified all of China. Song China had traded with its neighbors, the Liao and the Jin, but trade had been strictly controlled and limited to authorized border markets. The Mongol conquest therefore reintegrated China’s economy. The Mongol administration, in its desire to utilize the resources of the former Song territory, the most prosperous part of China, tried to promote internal trade and aimed at a fuller integration of north and south. The region around the capital was dependent on grain transports from the south, and large quantities of food and textiles were needed to keep the Mongol garrisons. The Grand Canal, which had linked the river systems of the Yangtze, the Huai, and the Huang since the early 7th century, was repaired and extended to Dadu in 1292–93 with the use of corvée (unpaid labor) under the supervision of a distinguished Chinese astronomer and hydraulic engineer, Guo Shoujing—an action entirely within Chinese tradition. This was preceded, however, by another measure in the field of economic communications that was unorthodox in Chinese eyes: about 1280, concessions for grain transport overseas were granted to some private Chinese entrepreneurs from the southeastern coastal region (some Chinese government officials were traditionally antagonistic toward private trade and enterprise, an attitude that the ruling Mongols did not share). These private shipowners transported in their fleets grain from the lower Yangtze region to northern Chinese harbors and from there to the capital. Early in the 14th century, however, these private fleet owners, who had made huge fortunes, were accused of treason and piracy, and the whole action was abolished. The Mongol government never replaced them with government fleets.

Another factor that contributed to the flourishing internal trade in China was standardized currency. The Song and Jin had issued paper money but only in addition to bronze coins, which had remained the basic legal tender. The Yuan government was the first to make paper money the only legal currency throughout the empire (1260). This facilitated financial transactions in the private sector as well as in the state treasuries. As long as the economy as such remained productive, the reliance on paper money as the basic currency had no detrimental effects. Only when the economy began to disintegrate under the last Mongol ruler did the paper money become gradually valueless and inflation set in. One reason for the paper currency might have been that much bronze and copper was used for the Buddhist devotion and its statues, another that metal ores in China proper were insufficient to supply enough coins for some 80 million people.

Daoism

Under the Jin dynasty several popular Daoist sects had flourished in northern China, and Genghis Khan had apparently been impressed by the Daoist patriarch Changchun. In 1223 Genghis Khan granted to Changchun and his followers full exemption from taxes and other duties demanded by the government; this was the first of a series of edicts granting special privileges to the clergy of the various religions in China.

For some time it seemed as if Chinese Daoism would win favor with the Mongol rulers at the expense of Chinese Buddhism. The Buddhists, however, also profited from the open-minded attitude at the court; they tried to win influence within the imperial family, prompted by the fact that many Buddhist institutions had been occupied by the Daoists, who relied on Mongol favor. Under the grand khan Möngke, several discussions were held between the Daoist and Buddhist clergy (1255–58), ending in a ruling that the former Buddhist temples should be returned to their original purpose. Imperial orders also outlawed some apocryphal Daoist texts, in which Buddhism was presented as a branch of Daoism and the Buddha as a reincarnation of Laozi, the founder of Daoism. But Daoism as such continued to exist under the Yuan, and the fiscal privileges originally granted to the Daoist followers of Changchun were extended on principle to all clergies.