Instead, it was the Southern Song Dynasty, with a narrow ruling area, just south of the Qinling Mountains and Huaihe River, and its land area was only two-thirds of that of the Northern Song Dynasty. During the Southern Song Dynasty, the middle and lower reaches of the Yellow River completely lost the traditional farming areas, and the income from land tax was greatly reduced, so the finance began to rely on non-agricultural industries.
Extended data:
By signing a maritime alliance with the Northern Song Dynasty, the Jin regime realized the decay and weakness of the Northern Song regime, and began to launch a large-scale attack on the Song Dynasty from the seventh year of Xuanhe (1 125). Song Huizong didn't dare to resist, afraid of being accused of national subjugation, so he told the emperor that he was located in his son Zhao Huan, namely Song Qinzong.
The invading Song Jinjun went south in two ways and soon surrounded Kaifeng, the capital of song dynasty. The rulers of the Northern Song Dynasty, headed by the emperor, were afraid of the enemy's surrender, so that in the first year of Jingkang (1 126), the nomads crossed the Yellow River, captured Kaifeng, and detained Hui Di and Qin Emperor in the Golden Temple.
On the first day of April of the following year, after the Jin nobles plundered Kaifeng City, they established themselves as puppet emperors, and took more than 3,000 people, including the emperor and his empresses, princes, imperial clan nobles, musicians and craftsmen, into exile in the north. He also took away court clothes, ritual vessels, armymen, bronze statues and many precious ancient books and charts. The Northern Song Dynasty perished.
Baidu Encyclopedia-The Change of Jingkang