They are all separatist forces in the south of the Yangtze River. Why didn't the Southern Song Dynasty put the capital in Nanjing?

In the ancient history of China, several regimes favored Jiangnan, such as Eastern Jin Dynasty, Southern Song Dynasty, Southern Qi Dynasty, Southern Liang Dynasty, Southern Chen Dynasty and Southern Song Dynasty. Almost all of these regimes leaning to the south of the Yangtze River are based in today's Nanjing, so Nanjing has the reputation of "the ancient capital of the Six Dynasties", "the golden powder of the Six Dynasties" and "the city of the Ten Dynasties".

However, among these regimes leaning to the south of the Yangtze River, only the Southern Song Dynasty did not make Nanjing its capital, but made Lin 'an (Hangzhou) its capital. Hangzhou can now rank among the "six ancient capitals", largely because of the Southern Song Dynasty. So it's all in the south of the Yangtze River. Why didn't the Southern Song Dynasty put the capital in Nanjing but in Hangzhou?

First of all, from the third year of Jianyan (1 129) to the eighth year of Shaoxing (1 138), the capital of the Southern Song Dynasty was now Nanjing, and later it moved to Lin 'an (Hangzhou). Throughout the Southern Song Dynasty, the nominal official capital was the Capital of the Song Dynasty (Kaifeng), the nominal temporary capital was Nanjing (the Southern Song Dynasty called it the East Capital, and later changed it to stay in the capital), and the actual capital was Hangzhou.

Secondly, the Southern Song Dynasty was established under the historical background of fierce fighting with the Northern Jin Dynasty. 8 8 Jin Jun broke through the natural barrier of the Yangtze River several times and entered the south of the Yangtze River. Song Gaozong and Zhao Gou fled to the sea to avoid being caught. Compared with Nanjing, which is close to the inland, Hangzhou has convenient conditions close to the harbor, which is conducive to the Southern Song Dynasty emperor to escape from the sea at any time.

Third, after several wars, the Southern Song Dynasty and the Jin Dynasty basically formed a pattern with the Huaihe River as the boundary. Compared with Nanjing, Hangzhou is farther away from the Huaihe River and naturally safer. During the Southern Song Dynasty, hawks always asked the imperial court to make Jiankang (Nanjing) its capital, because it was close to the Song-Jin border, which was beneficial to the Northern Expedition.

Finally, due to the loss of the north and the population explosion caused by immigration, the Southern Song Dynasty implemented a national policy of attaching importance to commerce, especially maritime trade. Since the completion of the Grand Canal, Hangzhou has gradually developed into the intersection of river transportation and sea transportation in China, and its economic position in the country is very important, which is one of the main reasons why Hangzhou is the capital of the Southern Song Dynasty.