Western Zhou, Eastern Zhou, Western Han, Eastern Han, Western Jin, Eastern Jin, Northern Song, Southern Song ... These are our usual names. Many people think that these are different dynasties. Actually, this is a misunderstanding. The Western Zhou Dynasty and the Eastern Zhou Dynasty, the Western Jin Dynasty and the Eastern Jin Dynasty, the Northern Song Dynasty and the Southern Song Dynasty are all one dynasty and one regime, but the same dynasty (regime) has different names at different stages.
These titles were acquired by later generations, not by the present.
Take the Western Han Dynasty and the Eastern Han Dynasty as examples. Since the founding of Liu Bang, it was named "Han" and later usurped by Wang Mang, and it was named "Xin". Later, Liu Xiu, a descendant of the royal family of the Han Dynasty, successfully revived the Han Dynasty, and the established regime was still called "Han", claiming to be the continuation of the Han Dynasty-although the Han Dynasty was actually ended by the new regime of Mang for nearly 15 years.
In fact, these two stages of the Han Dynasty were not called the Western Han Dynasty and the Eastern Han Dynasty at first, but the former Han Dynasty and the later Han Dynasty. Therefore, the history books before Wang Mang usurped the Han Dynasty were called "Han Shu" or "Qian", and the history books after Guangxu Zhongxing were called "Hou".
But in the Song Dynasty, the Song people began to call the Han regime established by Liu Zhiyuan in the Five Dynasties "the later Han Dynasty", which was similar to the regime established by Liu Xiu. In order to avoid confusion, the Song Dynasty called the former Han Dynasty the Western Han Dynasty and the later Han Dynasty the Eastern Han Dynasty, mainly on the basis that the capital positions of the two stages were different, with Chang 'an, the capital of the former Han Dynasty, in the west and Luoyang, the capital of the latter Han Dynasty, in the east.
As for the Song Dynasty, with the shame of Jingkang as the boundary, it was obviously divided into two stages. However, unlike Guangxu Zhongxing, Zhao Gou and Song Gaozong have never recovered the north of the Yangtze River, only half of the south of the Yangtze River. Officials have never called Hangzhou the capital, but called it "Hangzai", which means that Hangzhou is only a temporary administrative center. Sooner or later, we will recover our homeland and return to the Central Plains, and Kaifeng will still be the capital.
Since Hangzhou is not the capital, it can't be called the Northern Song Dynasty and the Northern Song Dynasty like the Western Han Dynasty and the Eastern Han Dynasty. So in the early Ming Dynasty, according to the division of ruling areas, the Song Dynasty before the shame of Jingkang was called the Northern Song Dynasty, and the Song Dynasty after it was called the Southern Song Dynasty.
Looking through historical materials, we can find that there are many "Han" regimes in history. It really takes a lot of effort to distinguish these regimes with the same name, such as Western Han Dynasty, Eastern Han Dynasty, Shu Han (Three Kingdoms Period), Cheng Han (Sixteen Kingdoms Period), Liu Han (Sixteen Kingdoms Period), Later Han Dynasty (Five Dynasties and Ten Kingdoms Period), Southern Han Dynasty (Five Dynasties and Ten Kingdoms Period) and Northern Han Dynasty (Five Dynasties and Ten Kingdoms Period) ... This is the "trouble" brought by the long history.