the Jin in 1234. Taking advantage of this, the Song army briefly recaptured their lost territory south of the Yellow River as the Mongols withdrew. However, a flood of the Yellow River, coupled with Mongol attacks, eventually forced the Song to withdraw. Seeking to conquer China, the Mongol Empire launched a series of attacks on the Song. By the 1270s, the Song economy had collapsed from the burden of taxes and inflation which the Song government used to finance its war against the Mongols. In 1275, the Mongols defeated the Song army near Xiangyang and captured Hangzhou, the Song capital, the following year. Song resistance ended at the Battle of Yamen, in which the last Song emperor drowned with the remnants of his navy. The destruction caused by the barbarian invasions in the later half of the Song represented a major setback in China's development. Yuan dynasty (1271–1368) The Mongol Yuan dynasty was the first foreign dynasty to rule the whole of China. As the largest khanate in the Mongol Empire, the emperors of Yuan had nominal authority over the other three Mongol Empires. This period of Pax Mongolica stimulated trade. However, millions of Chinese died because of the Mongol conquest. Under Mongol rule, approximately 65 million people were registered in 1290; in 1215, the dynasties of Jur'chen Jin and Song had registered populations of between 110 and 120 million. In addition, the Mongol government later imposed high taxes and extensively nationalised major sectors of the economy, greatly damaging what was left of China's economic development. In their conquest of China, particularly the north under Jur'chen Jin, the Mongols resorted to scorched earth policies, destroying entire provinces. Mongol forces carried out massacres in cities they captured, and one Khan proposed that all Chinese under Mongol rule be killed and their lands turned to pasture, but was persuaded against this by his minister Yelu Chucai, who proposed that taxing the region's inhabitants was more advantageous than killing them. Kublai Khan, after becoming ruler of China, extended the Grand Canal, connecting the Yellow and Yangtze rivers, to the capital, Beijing. This eased transportation between the south, now the hub of economic activity, and Beijing. This enhanced Beijing's status, it having formerly been a peripheral city, and was important to later regimes' decisions to have it remain the capital. The Yuan Government revolutionised the economy by introducing paper currency as the predominant circulating