Book of Sui
The Suí shū, or "Book of Sui," is an official dynastic history of China's Sui Dynasty (581-618).
The text contains the earliest usages of the word "Liuqiu" (J: Ryûkyû).[1] Though this was taken, within Japan at least, to refer unquestionably to the Ryukyu Islands, all the way up through the 1860s, an 1874 work by the Marquis D'Hervey de Saint-Denys questioned this identification, and sparked a debate as to whether this and other ancient Chinese references to "Liúqiú" in fact referred to Taiwan. The debate heated up only beginning in the 1920s, [2]