During the Xia and Shang Dynasties, Yi ethnic groups existed independently in the middle and upper reaches of the Yangtze River and created their own unique civilization, which was one of the protagonists of that era. Later, with the passage of time, the Yi primitive ethnic groups also merged with other ethnic groups, forming the main clan system of the Yangtze River civilization based on the "four ancient civilizations" in the middle and upper reaches of the Yangtze River, such as ancient Yunnan, ancient Shu, ancient Yelang and Chu.