The Star Dwellers: Terrestrial civilisation must remain stable for one hundred thousand years before it can be admitted to the galactic confederation. In 2050, ninety thousand of those years remain. The energy beings called Angels recommend to the confederation that it halve Earth's trial period. That would mean that about forty-five thousand years remain.
"A Dusk Of Idols": Forty-five thousand years remain. The confederation is referred to as "the Heart stars."
Mission To The Heart Stars: About three years after the events of The Star Dwellers, the confederation, which calls itself the Hegemony of Malis, decides instead to incorporate Earth immediately and by force but meanwhile Angels, Earthmen and other species begin to organize a rival federation...
Blish did not continue this series because in it he had already made the points that he wanted to make about the nature of civilization.
I had thought that "A Dusk Of Idols" was set five thousand years later and was compatible with the first novel though not with the second but a closer examination of the periods of time mentioned does not bear this out. "A Dusk Of Idols" is definitely set some time after the second novel because Earthmen have got used to traveling further into the galaxy.
There are three possibilities:
(i) "A Dusk Of Idols" is indeed compatible with the first novel though not with the second;
(ii) in the period of the short story, Earth is still resisting and organizing against the Hegemony but concealing these activities from many of its citizens;
(iii) both the forceful annexation and the rival federation have for reasons not divulged to the reader been abandoned so that Earth has returned to merely a trial status with respect to the Heart stars.
The two novels are very effective as juvenile science fiction whereas "A Dusk Of Idols" is an extremely effective adult short story yet Blish was able to use the same background for both. In the short story, the protagonist sees the totem poles of doomed cities erected in a vast underground sea on the planet Chandala and concludes, "'The totems are falling all around us as we sit here. One by one...one by one.'" (Blish, Anywhen, New York, 1970, p. 135).
