Dai Chao Song
Xia and Shang Dynasties, Western Zhou Dynasty and Eastern Zhou Dynasty are divided into two parts. Spring and Autumn and Warring States unified Qin and Han Dynasties; Three points in, two points before and after the delay; The Southern and Northern Dynasties coexisted, and the Sui, Tang and Five Dynasties passed; After the Song, Yuan, Ming and Qing Dynasties, the royal family ended here. -Excerpted from History Textbook for Primary Schools (1990s edition).
Xia, Shang and Zhou were all independent regimes before they were called dynasties, but they were not called dynasties, so the history of Xia, Shang and Zhou only began with "overthrowing the previous dynasties and becoming * * * emperors". Since Wei, Jin, Southern and Northern Dynasties, no matter whether the world is unified or not, it has been called Korea. However, these divided regimes often do not recognize each other's qualification to be called North Korea.
In China, some dynasties were established before the demise of the previous dynasty, so the duration of some dynasties overlapped. For example, Li Yuan announced the establishment of the Tang Dynasty in 6 18, and the Sui Dynasty officially perished in 6 19.
Refer to the above? Baidu encyclopedia-dynasty