Liu Che, the Emperor of the Han Dynasty, issued an important decree to weaken the power of governors. Since the scene of Kawachinoayanofumi, how to limit and weaken the expanding power of the vassals has always been a serious problem faced by feudal emperors. During Emperor Wendi's reign, Jia Yi put forward the suggestion of "building more princes, but limiting their forces" in terms of public security policy. The specific method is to divide the vassals into several countries, and let the descendants of the vassals take turns to share the fiefs until the land is exhausted; If the land is vast and there are few children and grandchildren, the name of the founding of the People's Republic will be falsely established, and the grandson will be enfeoffed after birth. Originally, the county system was implemented, and the favor system was improved on the basis of the county system. In the areas under the jurisdiction of former governors, only the eldest son inherited, but the eldest son, the second son and the third son inherited together.