This article questions the prevailing tendency to understand premodern Chinese sovereignty primarily through universalist claims of rule over โall under Heaven(tianxia).โ By examining the Tang Code, it argues that sovereignty in Tang legal thought was not only universal but also territorial and jurisdictional. The concept of guo ๅ, as defined in the Code, designated the Tang polity as a spatial domain demarcated by fortified borders against external incursions, and regulated through laws on treason, border control, and unauthorized crossings. While Tang emperors employed cosmological rhetoric to assert supreme authority abroad, the legal order simultaneously articulated sovereignty in bounded, spatial terms. The study highlights the layered character of Tang Sovereignty, combining jurisdictional diversity, territorial control, and universalist ideals. In addition, it shows how Tang law contributes a distinct juridical perspective to wider debates on the interplay of guo and tianxia in Chinese political thought.