The term guo, which meant "dynastic state" in classical Chinese, has been used to signify the modern "nation-state" since the mid-nineteenth century. Yet across epochal transformations-from late Qing constitutionalism to Republican ethno-civic nationalism to Mao Zedong's class nation-guo's lingering association with "regime" continued to shape Chinese efforts at nation-building, with far-reaching consequences.

Defining China offers a cultural and legal genealogy of guo, examining how modern China, Chinese nationalism, and Sino-foreign relations have been shaped by this multifaceted concept. Mara Yue Du reads the premodern meanings of guo into the modern period, rather than projecting the modern sense of "nation" back onto the past. In doing so, she reframes modern Chinese history as a deeper contest between two competing conceptions of Chineseness: one shaped by China's maritime connections, which brought Confucianism into dialogue with Western constitutionalism, and the other grounded in China's agrarian heartland and its enduring tradition of Legalist statism, which proved surprisingly compatible with Marxism-Leninism.

By tracing the opportunities and tensions that emerged from the translation of this key concept, Du offers an ambitious reinterpretation of Chinese nationalism in Chinese terms. Connecting the fate of twentieth- and twenty-first-century China to premodern Chinese political thought, this book sheds new light on how linguistically coded local ideas have become entangled with an evolving global order, using China as a case study for revisiting fundamental questions in global history.