Why did early chinese civilizations and dynasties thrive for thousands of years with little outside influence?

The history of China, one of the oldest civilizations in the world with continuity to the present, has its origins in the Yellow River basin, where the first Xia, Shang and Zhou dynasties emerged. The existence of documents written about 3500 years ago has allowed the development in China of a very precise historiographical tradition, which offers a continuous narrative from the first dynasties to the contemporary age. The Chinese culture, according to the myth, is inaugurated with the three original emperors: Fuxi, Shennong and finally the Yellow Emperor Huang, the latter considered as the true creator of the culture. However, there are no historical records that demonstrate the real existence of these personalities, which according to the oral transmission from generation to generation, would have lived about 5000 to 6000 years ago. This civilization had little influence in its beginnings due to the great number of internal problems that had as it was the time called The Warring States Period, in which several kingdoms fought for power, it ended with the unification of China by the Qin dynasty in 221 a. C.