The small print of Xianbei of Emperor Wendi of Sui Dynasty is that Xianbei's surname is Pu. After Emperor Wendi came to power, he restored the Han surname "Yang".
Extended data:
After the demise of the Northern Zhou Dynasty, the Xianbei State, with Xianbei as the main body, ceased to exist. After Sui and Tang Dynasties, Xianbei no longer existed as a political entity and a national entity. Now, the Xianbei ethnic group has merged with other ethnic groups and become another ancient ethnic group that has disappeared on the road of ethnic integration. However, the Sinicization policy of Xianbei people is not particularly successful on the whole, and some Xianbei people are sinicized first and then Hu Hua.
The Han people in Sui and Tang Dynasties, or "Tangren", are no longer a simple continuation of Han descent before Wei and Jin Dynasties, but a mixed ethnic group with Hu and Han descent. The society of Sui and Tang Dynasties, composed of the same nation, broke through the rigid unified pattern and presented a vivid pluralistic situation.
References:
Baidu encyclopedia-Xianbei nationality