First, the Huns themselves are a mixture, not a nation of pure blood.
In the north, there used to be many nomadic people. Because of their nomadic lifestyle, they often exist in the form of tribes. One of them rose in the southern forest region of Siberia and expanded its territory rapidly. Later, it basically unified the northern grassland and desert. It is said to be unified, but it actually exists in the form of tribal alliance, unlike the Qin and Han Dynasties when counties ruled the world. There are many tribes in it. They have similar languages, basically no writing, similar lifestyles, and have the habit of living by aquatic plants. Compared with the Han nationality in the Central Plains, this ethnic group has larger head, wider forehead, smaller eyes, flatter nose and thicker lips, and has the characteristics of Caucasian race and Mongolian race. But we can be sure that the Huns are not a nation, but a huge tribal alliance living on the grassland.
Second, the Khitans in Liao country are also mixed-race, but the main force comes from Xianbei.
Speaking of the Khitans, we have to say Xianbei, a Yuwen department with a good relationship with the Northern Wei Dynasty. They belong to six Xianbei tribes of Xianbei nationality. After the establishment of the Northern Wei regime, Tuoba Xianbei maintained an alliance with Yuwen Xianbei in the northeast to deal with Wen Liang, who was once their slave. However, after being defeated by Murong Xianbei, they moved into the Liaohe River basin in large numbers, and did not quit the historical stage, becoming the ancestors of the Eight Qidan Departments in Liaodong. In the Five Dynasties, the Khitan formally rose and unified the North. But at this time, Qidan was descended from Xianbei people, Uighur tribes and even some descendants of Koguryo.
Third, the Mongols and the Khitans share a common ancestor.
Mongols come from Shiweibu, and both Shiweibu and Qidan have a common ancestor Xianbei people. At that time, Shi Wei lived in the west of Xing 'an Mountains, and Qidan lived in the east of Xing 'an Mountains. Pyrrosia mainly has the ancestry of Xianbei people in ancient times, while combining some ancestry of Rouran people. However, Rouran people themselves are mainly Donghu people, and have the same lineage as Xianbei people. As an important force developed by Xianbei people in ancient times, Mongolian Shiwei eventually unified the grassland, formed the Mongolian nation, and then unified China, almost conquering the whole world.
In fact, it is hard to say who is the descendant of whom, and the tribal management style. Unlike the Han people, the relationship between them is different. One tribe is the boss and has enough political height. Then the name of this tribe is the standard name of the whole regime management area.