歷來學界多將散布於幽并兩州的烏桓視為一族群，考察其興起、發展與衰敗。唐長孺、田餘慶注意到不同地域的烏桓會因族群互動複雜性而有不同發展。本文承襲此論，指出代北地域的上谷烏桓之重要性，考察東漢至北魏初上谷、上谷以東諸郡與上谷以西諸郡等三類烏桓的歷史。東漢初上谷烏桓在位於入塞要道的白山為東漢守邊，且因與中原貿易優先權而成為最強富的烏桓部落。隨著匈奴破滅，鮮卑崛起，檀石槐也以白山為根據地尋求資源。東漢朝廷不願上谷烏桓強大，故將其內徙。該部仍扼守入塞要道並壯大，迫使鮮卑以略邊、互市取得資源。西晉至北魏，上谷烏桓與拓跋部共生。上谷以西烏桓因與匈奴、鮮卑、氐、羌互動，被稱為「雜胡」，也有如鐵弗部、獨孤部等具匈奴背景部落被稱為烏桓。東漢末上谷以東烏桓諸部曾組成三郡烏桓部落聯盟，被曹操擊破後為東部鮮卑諸部吸收，在五胡十六國政權中屢任要職。

The Wuhuan, a nomadic people who inhabited Youzhou and Bingzhou, have generally been regarded as one group, but modern scholars have observed differences between the Wuhuan in different areas. Building on this research, this study argues for the importance of the Wuhuan, examining three groups, residing in Shanggu commandery, to its east, and to its west, from the Han through the Northern Wei. At the beginning of the Later Han dynasty, the Wuhuan of Shanggu commandery was the strongest and richest of the Wuhuan tribes, guarding the White Mountain passage into the Central Plains and exchanging goods with the Han. With the rise of the Xianbei, Tanshihuai took White Mountain as a base area and the Han moved the Wuhuan of Shanggu toward the interior. In the last years of Han, the Wuhuan of Shanggu was still the strongest in all Wuhuan tribes. At the same time, the Wuhuan of Shanggu and the Tuoba built a symbiotic relationship. Empress Dowager Qi (祁) and Empress Dowager Wang (王) had great influence in Tuoba, which had shared origins with the Wuhuan of Shanggu.