According to historical analysis, the reason is that the geographical locations and systems adopted by the two major tribal alliances at that time were different:
The tribal alliance of Emperor Yan followed the elder system of previous dynasties, that is, it adopted a relatively loose and democratic elder system. Parliamentary system, decentralized power. This system promoted the development of agriculture, art, music, medicine and other cultures. Because it is located in the relatively flat middle and lower reaches of the Yellow River, which is mainly engaged in farming, fishing and hunting, and has abundant and diverse food, the tribal alliance is relatively friendly and lacks aggression.
The Yellow Emperor's tribal alliance used a patriarchal system, also called centralization. All actions were arbitrarily carried out by the leader of the alliance, and power was concentrated. Because it is located in the relatively barren middle and upper reaches of the Yellow River, the food is monotonous, mainly hunting, and the folk customs are strong, so they are better able to exert their combat effectiveness in wars. After defeating Chi You, the Yan Emperor tribe wanted to become the overlord, and had another big conflict with the Yellow Emperor tribe. The two tribes, Emperor Yan and Emperor Huang, fought another battle in Banquan (now in Huailai, Hebei Province, adjacent to Zhuolu). As a result, Emperor Yan was defeated and submitted to the tribe of Huangdi. Later, the descendants of this unified tribe of the Yellow Emperor developed southward from the Hebei area, entered the Yellow River Basin, and settled in the Central Plains. After a long period of living together, they multiplied and merged with each other, and together they formed China. The ancient residents of the Central Plains region laid the historical foundation for the later Chinese people. In the long process of historical development, because the Yellow Emperor's tribe was relatively powerful and culturally advanced, and because the Yellow Emperor was the ancestor universally respected by all ethnic groups, many of the inventions and creations of primitive society were concentrated in the Yellow Emperor's period, recorded in Under the name of Huangdi, Huangdi became the representative of Central Plains culture. Later, this tribe gradually developed, and residents with different ancestors living in the Central Plains area all considered themselves descendants of the Yellow Emperor. After the Spring and Autumn Period (770 BC to 476 BC), these residents called themselves the Huaxia ethnic group, and after the Han Dynasty, they were called the Han ethnic group. Later generations of the Han people respected the Yellow Emperor as their ancestors and called themselves "descendants of Yan and Huang".