The system of appointing ethnic Yi people's hereditary headmen ran through Yuan and Ming dynasties, and Yuan dynasty witnessed the full implementation of that system. Later in the national border regions inhabited by ethnic groups a system of parallel government by both hereditary headmen and government-appointed officials began to evolve. Nevertheless, in the eyes of feudal dynasty rulers that system remained still an expedient approach to pacify the border region's ethnic groups. Reaching its heyday in Ming dynasty, that system in its political organization forms had been fit into a unified and centralized government of Ming dynasty, while in the domain of the hereditary headmen rule, its political and economic structures still kept regional ethnic characteristics. After the middle term of Ming dynasty reign, as centralized control of the southwestern Yi populated regions further strengthened, the so-called "change of hereditary headmen rule to government officials' governance" took effect progressively.