My interpretation, seeing that it is propaganda, was to create an image of a China that didn't exist in 1979. China was at that time still fresh from the cultural revolution and still mostly closed to the world. Propaganda had switched from "revolution" and the Mao personality cult to more moral-boosting messages. Even though the China in this poster was a fantasy, I'm sure it was successful to some degree in making some of the masses proud to be Chinese.