Based on the concept, connotation and extension analysis of ethnic groups and tribes, this paper had pointed out that ethnic groups evolve with the advancement of history. This paper had traced the origin and development of Xianbei Tribe in China, describes the origin of Xianbei Tuoba Tribe in detail, analyzes the development process of Tuoba Xianbei Tribe, and had analyzed the overall reasons and motives of the Sinicization of Tuoba Xianbei. It would had been pointed out that the overall sinicization of Tuoba Xianbei conforms to the historical development process, would be Tuoba Xianbei's voluntary, active, peaceful, positive, comprehensive and thorough, which was Tuoba Xianbei's correct historical choice, and it would help all nations in the world correctly understand the concept, connotation and extension of nationality. It would provide a typical attitude, method and approach for all ethnic groups in China and the world to correctly deal with ethnic issues, would provide a case and model for the peaceful development of China and even the peaceful development of the world, and also would provide historical facts and theoretical basis for ethnic integration.