For much of imperial Chinese history, chroniclers and explorers understood a maritime land called Liuqiu to be the Ryūkyūs. In the early twentieth century, however, a new dynastic history claimed that Liuqiu was in fact Taiwan. This article explores how and why an uncontested and unambiguous understanding of Chinese maritime history was suddenly rewritten in the modern world, becoming the accepted interpretation and shaping twenty-first century geopolitics. While scholars have weighed the veracity of Liuqiu as either Taiwan or Ryūkyū, this article focuses on how the Liuqiu–Taiwan thesis was produced and transmitted, showing how scientific methodology, imperialism, and nationalism worked to reshape geographical history. The article further contributes to an understanding of the shaping of the borders and claims of the modern Chinese nation: whereas scholars have investigated late Qing and early Republican debates over the western frontier and ethnicities, this article shows that questions over Taiwan were just as important.