No, some Mongolian people directly use Han surnames.
There are four main sources of Han surnames of the Mongolian people:
1. Taking the name of the tribe as the surname.
2. Use the clan name as the surname.
3. Use the ancestor’s name as the surname.
4. Directly use the Chinese-translated surname as the surname, such as directly using Chinese surnames such as Wang, Li, Liu, and Zhang. Extended information
Mongolian Han surnames appear in areas where Mongols and Han are mixed. Pure Mongolian areas do not have Han surnames, only Mongolian surnames. Generally, people from this tribe take tribal surnames when they move to other tribes, or when their tribe merges into other tribes. Since the Yuan Dynasty, many Mongolians have adopted Chinese surnames and names, mainly out of the need for ethnic exchanges.
By the Ming Dynasty, many Mongolians adopted Chinese surnames, especially the Mongolians who were scattered throughout the country or in areas adjacent to areas inhabited by Han people. Today, surnames still play an important role in people's interactions. When in contact with each other, you can call them by their first name or last name. Mongolian Chinese surnames are generally produced in three ways: homophony, transliteration, and self-selection.
The homonym is to choose a certain syllable of the Mongolian surname. The fixed transliteration is to translate the Mongolian surname into Chinese and use one character of it as the Chinese surname; the other is to choose characters, such as Wengniute, they think Wengniute He belongs to the Gao family, so his Chinese surname is Gao. Due to the inconvenience of transportation and communication at that time, people of the same ethnic group in different areas did not have time to discuss in the future, so the same Mongolian surname may have different Chinese surnames in different areas.
Baidu Encyclopedia-Mongolian surnames