Answer:
The first feudal king in Chinese history was the Qin Dynasty, which ruled for a total of 15 years. The main reason for its demise was that after the death of Qin Shi Huang, Zhao Gao tampered with the imperial edicts with Qin Er Shi, who succeeded to the throne, and then Qin Er Shi acted arbitrarily abetted by Zhao Gao, leading to the civil uprising and eventual demise.
Step-by-step explanation: