Mongol conquest of the Song dynasty

The Mongol conquest of the Song dynasty was a war of more than four decades, from 1235 to 1279, in which the Mongol Empire and its successor in China, the Yuan dynasty, overcame the Southern Song, the richest and most populous state of its time. Begun under the great khan Ögedei and completed under Kublai Khan, it brought all of China under a single foreign dynasty for the first time and was the last great conquest of the Mongols.

By the early thirteenth century China was divided. The Song dynasty ruled the south from its capital at Lin'an, today's Hangzhou, having lost the north a century earlier to the Jurchen Jin dynasty. After Genghis Khan began attacking the Jin in 1211, the Song saw a chance for revenge, and in 1233 Song troops joined the Mongols in the final siege of the last Jin emperor at Caizhou. The Jin fell in 1234. The Song then tried to seize the former northern capital, Kaifeng, but were driven back by Mongol forces, and in 1235 open war began.

Unlike the steppe and the plains of the north, southern China was crossed by rivers, lakes and rice paddies and defended by walled cities and fortresses. The Mongols could not rely on cavalry alone. In the first phase they raided deep into Sichuan, sacking Chengdu, and fought for control of Xiangyang on the Han River, which changed hands more than once. The war slowed after Ögedei's death in 1241 and during the Mongol succession disputes that followed.

In 1258 the great khan Möngke launched a major offensive. He led an army into Sichuan himself, while his brother Kublai advanced in the centre and the general Uriyangkhadai came up from the south through Yunnan, where the Mongols had already conquered the kingdom of Dali. Möngke died in August 1259 while besieging the Diaoyu fortress near Chongqing, of illness or, according to some accounts, of a wound. Kublai was besieging Ezhou on the Yangtze at the time; he made a truce with the Song minister Jia Sidao and returned north to secure the succession, which he won after a civil war with his brother Ariq Böke.

Kublai renewed the war in 1268 with a siege of the twin cities of Xiangyang and Fancheng, which guarded the route to the Yangtze. The siege lasted until 1273. Kublai built a large river fleet with the help of Chinese defectors, and engineers from the Ilkhanate in Persia built counterweight trebuchets whose heavy stones battered the walls; Fancheng fell and Xiangyang surrendered soon afterwards. In 1271 Kublai had proclaimed the Yuan dynasty in Chinese style.

The Mongol commander Bayan then led the main army down the Yangtze. Some cities resisted and suffered massacres, as at Changzhou in 1275, while many others surrendered. In 1276 the regents at Lin'an surrendered the capital and the boy emperor. Loyalists fled south with two younger princes and kept up resistance along the coast. The minister Wen Tianxiang was captured and later executed for refusing to serve the Yuan. In March 1279, at the naval Battle of Yamen near modern Guangzhou, the last Song fleet was destroyed, and the official Lu Xiufu leapt into the sea with the child emperor Zhao Bing.

The Yuan ruled a reunited China until 1368. The conquest was costly, with heavy losses in Sichuan and other contested regions, although historians caution that falls in recorded population reflect migration, disease and incomplete registers as well as killing. Kublai's later attempts to extend his rule overseas, to Japan and elsewhere, largely failed.

Our 1200 map shows a divided China with the Song in the south, and the 1279 map shows the whole country under the Yuan in the year the conquest ended.