本文的目的是藉由《唐律．名例律》中的「化外人」條的考證，探究唐代的國籍制度，進而分析當時東亞的「國」概念。本文首先討論《唐律》的「化外人相犯」條。重點有三。一是說明「化內」與「化外」在制度上的判準是戶籍。二是分析「化內／化外」與「國內／國外」的關係。就這點而言，唐律明確地將中國的郡縣區域定義為一「國」。在唐朝官方文書中，所謂的國名，一般只有在對照外國時才有標示的需要，如中國與唐國。三是分析《唐律》中所謂的化外人的狀態。本文認為條文中所說的化外人是公務來中國的外國人，也由此推唐代法律制度依教化的理念，不預設中國境內有化外人，或所謂外國人。其次，本文從東亞國際秩序的視野，討論「國」的定義為何，也由此論證東亞一方面存在著「列國並立」的秩序，另一方面各國間的地位不平等，而此不平等的地位表現在國君為帝或王。最後，本文也將《唐律》中的國的定義對照天下秩序，說明皇帝制度的二個面向，亦即「天下-國-家」的世界觀。

This paper analyzes the concept of nationality (guo, guojia) in the Tang Dynasty based on an interpretation of the laws regarding ‘offences among the barbarians (huawai ren)’ in the Tang Code. Three key points can be distinguished. First, although the idea of barbarians is based on a cultural distinction, in practice the criterion was household registration. Second, the legislators of the Tang Code had a clear definition about two kinds of guo, domestic and foreign. The areas of zhou (prefecture) and xian (county), which were ruled by Chinese emperors, constituted one domestic guo. Third, this paper discusses the identity of these so-called huawai ren. I would like to emphasize that the term huawai ren in clauses of the Tang Code does not refer to foreigners in the common sense, but mainly to diplomatic envoys in public service from foreign countries, including monks and students. Based on this analysis, this paper demonstrates that a system of states did exist in ancient East Asia, although these states were not equal in stature, the heads of the greater being known as di (emperor) and the lesser as wang (king). The paper concludes by juxtaposing the Tang Code’s idea of guo with the concept of “empire” (tianxia), arguing that ‘tianxia-guo-jia’ is a valid framework for understanding the Chinese imperial polity.