I want to expand on Turkic, Mongol and Tungunzic a bit. Languages here, Altaic, could be used for sorting through ancestry. However, past experiences show that invader's lingua franca might not always prevail. The number count. That is, the ethnic group which possessed the majority head count would ultimately dominate the tongue spoken.
The nomadic Altaic language speaking people had been roaming the Euro-asian continent before prehistory. Huns were recorded to have been driven away from Hetao areas by Qin's first emperor. No recording of significant goernment as to the Huns existed till the times of Chanyu Modu or Modok. Modok was recorded to have first defeated five northern tribes in Siberia and Mongolia, and then attack Yuezhi in the east and Donghu in the east. Then, he attacked Loufan and Baiyang in the south and continue on to retake the land from which they were driven away by Qin. Chinese history said Yuezhi was more powerful than Huns, and Modok's father had to send in hostage to Yuezhi. We could speculate that the Rongdi people, who were driven away from Hetao, would somehow possess a better knowledge and intelligence than the Mongolian nomads roaming from the Altai to Manchuria. A person like Modok would be responsible for uniting the northern steppe people into a strong Hunnic empire, the same way the later Turks and Mongols had undertaken in forming their empires. When Rongdi (including Chidi and Baidi) fled to Mongolia, they brought with them their knowledge of civilization and government from the Yellow River, but whatever Rongdi people's tongue could be overtaken by the prevalent lingua franca of the steppe, i.e., Altaic language.
Still, I don't see any significant Caucasian element among the Huns. Sima Qian's Shi Ji had no record about Modok's physical features. I will speculate that the Huns in the west might have changed after they raided into Chinese Turkistan and mixed up with remnant Yuezhi.
I had noticed a kind of enthusiasm about the so-called 'Blue Turks' versus 'Black Turks'. There is no such terminology as Blue Turk in Chinese records. The Turks were said to have fled to the Altai when Toba destroyed a Hunnic statelet called Juqu, a dynasty called Liang in China's Sixteen Nations ime period. They worked for the Ruruans as iron miners. They carried the so-called Ashina family name. 200 years after that, Tang records still made difference between Ashina people and the Hu people. Chinese used 'Hu' s acategorical designation for the nomads but also used it specifically for the Huns. When a difference was made to claim that a Turkic chieftan called Simo looked more like a Hu than an Ashina, it pointed to the possibility that Ashina possessed features that the Hu people didn't have, i.e., high nose bridge and deep socket eyes.
Enthusiasm will stop here. It would be the later Kirghiz who were said to have things utterly different, i.e., red hair and green eyes. The Huns were said to have conquered this Jiankun statelet in the west and assigned a Chinese defector general there. This general was called Li Ling and Chinese records said that those Kirghiz who carried balck hair would be Li Ling's descendants. Li Ling was assigned to the land of Jiankun as Hunnic so-called rightside virtuous king. 800 years later, the Kirghiz came to Mongolia to fight the Uygurs, and they said they shared the same last name as Tang emperor, Li.
In last section, I touched on the Tungusic people, i.e., Fuyu, Koguryo and Koreans/Manchus. I should have been clearer here. There was an anceint statelet calle Sushen bordering Japan Sea 3000 years ago. They are the ancestors of all Tunguzic peoples in Manchuria and Korea. I could not tell what langauge Sushen would speak. They might not be related to later Donghu people. Donghu people were defeated by Modok and they fled to Liaoning Province, Southern Manchuria, as well as to northern Khing'an Ridge, somewhere near the Huron Lake. They were called Xianbei and Wuhuan. Xianbei, while joining forces in sacking China in 4-5 th centuries, would raid into Korea peninsular as well. Xianbei conquered Pyong'yang several times and dug up the tomb of Koguryo royal house. Those Xianbei must have mixed up with the Sushen and Koreans in southern Manchuria and hence the Tungusic language had taken hold in Korean peninsular and indirectly influenced Japanese a bit. I had reservation about Sushen's tongue because this area was part of the Sino-Tibetan Chinese influence. Shang Dynasty's prince Ji Zi was recorded to have been dispatched to southern Manchuria and Korea as a ruler.
The Xianbei people, around the Amur River and Heilongjiang River, would include later Shiwei Mengwu, i.e, ancestors of Genghis Khan. The photo,
http://www.uglychinese.org/pic1.jpg, which I am temporarily uploading onto the site, had a classmate on the rightside. He is from the Sibo group, a group of northern Manchurians who were ordered to march to Chinese Turkistan as garrison troops. You could tell his face is closer to today's Mongols and maybe similar to Genghis Khan himself. (Genghis Khan's people might have mixed a bit with the Kirghiz people who had expelled Uygurs in the middle 9th century). I believe I had touched on all three branches of people in the steppe. If any of you have a different opinion, please do not hesiatte to share it with me.