Abstract: The real situation of ancient Chinese dynasties, which does not fit into the Western concept of empire, shall be understood with some concepts revolving around the notion of tianxia, the ancient Chinese version of cosmopolitanism. After the collapse of the West Jin Dynasty, the East Jin Dynasty obtained its legitimacy in the consensus of tianxia of the Han people and other ethnic groups. Although its real power was far away from that of an ideal tianxia, the East Jin Dynasty, at least formally, did maintain a tianxia regime due to the tianxia consciousness of its surrounding ethnic groups. All of MURONG Xianbei, Koguryo, and other tribes in the northeast remote from the center of the East Jin confined themselves to the consciousness of tianxia despite the fact that they chose different ways to build their states. Different from the unified “tianxia without boundary” of the Han and West Jin Dynasties, the tianxia of the East Jin consisted of numerous political powers sharing a same tianxia consciousness. Enlightened by the term of the “shadow empire” in Thomas J. Barfield, this thesis describes such a new tianxia system as the “shadow dynasty”, which was comprised of various political regimes restrained by the central imperial court.