Ryukyu was not merely a vassal state to China; it was also a deeply integrated part of Chinese civilization, noted Hu Huanyong, who is renowned worldwide for proposing the Hu Huanyong Line, a demarcation of China's population geography.

In his book "Taiwan and Ryukyu," the founder of modern Chinese human geography traced the historical roots of Ryukyu, including its relations with China. In it he said it is a kind of civilization and political community formed through long-term institutional connections that could not be severed by military conquest, and a solid historical foundation for the assertion of rights.

From listing key post-war documents such as the Cairo Declaration to weighing Ryukyu's importance to China's sovereignty and strategic security, he also made important proposals in other books on establishing an order that would guarantee China's fundamental interests and the lasting peace of East Asia.

Despite the fact these books were published in the 1940s, their breadth and depth of thought still hold significant implications to this day. They are to be included in "Hu Huanyong Collection of Works," which is soon to be officially published.