There was an 80-year gap between The Return of the Condor Heroes and The Heaven Sword and Dragon Sabre. The answer to the question of what important things happened during this period depended on one's definition of " important." Here are some possible answers: - During this period of time, there might be some major events or historical events such as the civil war between the two countries, the War of Resistance against Japan, the cooperation between the two countries, the founding of the People's Republic of China, etc. These events might affect the background and plot development of the novel. - During this period of time, there might be some new literary works or novels that might have an impact on the plot and character settings of the novel. - During this period of time, some new historical events or characters may appear, and these events and characters may become the plot clues or key characters of the novel. It's important to note that these are just possible answers. There are actually many other possible factors in novel writing and historical research.