The Mengwu Shiwei were not Mongols after all…
When people describe the early mongols, they usually refer back to an obscure tribe of people called the Mengwu Shiwei (identified in the old book of Tang). These people are labaled as the direct ancestors of the Mongols based only on phonetic match between Mengwu and Mongol.
However, if you look at the Chinese description of their geographic location, material culture, and lifestyle they resemble Tungusic hunter gatherers more than ancient Mongols.
In the book of Sui the Shiwei are described as not horse-riding, but forest hunter gatherers. The book of sui says that the shiwei wore hide clothing made from fish skins and wore wooden skis across the ice. They wove bark to make boats, and tied ropes to dogs to pull their sleds. Furthermore, they lacked horses and sheep.
In the book of Jiu Tangshu, the Mengwu Shiwei, are located south of the wanjian river on the edges of the Mohe (tungusic) border on the Amur river basin.
Because of these descriptions some wild wild ideas have been circulating about the Mongol origins, however things become much clearer when we look at the inhabitants of the Amur river basin.
In the 19th century Russian ethnographers first studied the lower Amur River, and they found a culture that exactly matches the material culture from the book of Sui and the descriptions point-for-point of the Shiwei. These people were not the Mongols, but the Ulch and Nanai People.
When the ethnographers interacted with these people, who later became the Ulch, they introduced themselves as the Mangun people.
In their language:
Mangu-name of the Amur River (ma- meaning big and gu- meaning river)
N-possessive case ending (agglutinative structure of the language)
In the Ulch language Mangun meant the people who live on the Amur river, and that is what they called themselves prior to Russian colonization. (Reisen und Forschungen im Amur-Lande, 1881)
Essentially, it is very evident that the Mnegwu Shiwei of the Tang records were not Mongols or ancestral Mongols. However, they were the Tungusic people living along the Amur river system.