What ethnic group were they during the Tang Dynasty?

Han nationality. The Li family, a royal family in the Tang Dynasty, was a family with Xianbei blood. The Li family was a great aristocrat in Longxi and was highly used in the Northern Zhou and Sui dynasties. For example, Li Yuan's father, Li Hu, was powerful and powerful at the beginning of the Northern Zhou Dynasty.

Even in Yuwentai’s "movement" to restore the old Xianbei surname, he was assigned a Xianbei surname - Daye, and became a trusted noble of the Northern Zhou Dynasty. Of course, this surname has nothing to do with Li Hu's name. It's a joke when you read it in succession. This name, which seems suitable for living in a wildlife reserve, does not mean that Li's ancestors are Xianbei or non-Han.

Ancestors of the Han nationality:

According to the legends recorded in pre-Qin documents and the scope of the capitals of Xia, Shang and Zhou Dynasty, the ancient ancestors of the Han nationality generally lived in the Central Plains area; they were mainly distributed here The two types of Neolithic culture, Yangshao Culture and Longshan Culture in a region, are generally considered to be the cultural relics of the ancient ancestors of the Han people.

Ancient legends also describe that the ancestors of the Han nationality experienced a long period of primitive commune system. Before the Yellow Emperor, the tribes had gone through the stage of matrilineal clan tribes that "knew their mother but not their father"; the legend about the Yellow Emperor marked the transformation from matrilineal clan tribes to patrilineal clan tribes, and had entered the stage of tribal alliances.