The Song dynasty reëstablished unity around 960. Under the Song, the prosperity of South China began to overtake that of North China. After the north was lost to the Jurchen Jin dynasty in 1127 following the Jingkang Incident, Hangzhou became the capital of the Southern Song under the name Lin'an. Renowned for its prosperity and beauty, it may have been the largest city in the world at the time. From then on, north Zhejiang and neighboring south Jiangsu have been synonymous with luxury and opulence in Chinese culture. The Mongol conquest and the establishment of the Yuan dynasty in 1279 ended Hangzhou's political clout, but its economy continued to prosper. Marco Polo visited the city, which he called "Kinsay" (after the Chinese Jingshi, meaning "Capital City") claiming it was "the finest and noblest city in the world".

When did the Song dynasty reestablish unity around?