The History of Ythrians

In relation to the History of Technic Civilization, there are seven distinct stages:

humans discover the planet Ythri;
Ythrians adopt Terran technology;
Ythrians and humans jointly explore the planet later called Avalon;
both species colonize Avalonian islands;
both species colonize the main Avalonian continent;
both species resist the Terran Empire to keep Avalon in the Domain of Ythri;
an Avalonian Ythrian spies for both Domain and Empire.

Having been told this much, we want to know more. This Ythrian narrative, enough to comprise a short future history, instead crosses over with the narratives of van Rijn, Falkayn and Flandry:

van Rijn travels in an Ythrian ship;
the colonization brings together earlier stories of interstellar exploration with the story of Falkayn's response to the decline of the Polesotechnic League;
the story of resistance to Imperial annexation brings together the narrative of the early Empire with the earlier stories of the colonization;
the Avalonian spy features in a sequel to a Flandry novel.

Thus, four series form one series which is more than the sum of its parts. Apart from Ythrians, van Rijn, Falkayn and Flandry, another significant name is Argos:

Manuel Argos founds the Terran Empire;
the Empire expands;
it fails to annex Avalon;
Flandry defends it;
it eventually falls -

- and the name associated with the post-Imperial Long Night is Roan Tom. Unlike the others mentioned here, Manuel and Tom are not series characters but could have been as could Daven Laure of the post-Long Night Commonalty period. There is no direct link between, e.g., first contact with Ythri and Daven's contact with the descendants of rebels expelled by Flandry. Nevertheless, these stories are earlier and later episodes of a longer narrative. In fact, they were respectively the earliest and latest episodes until Anderson wrote an even earlier story set during the exploration of the Solar System.

Anderson wrote his series from 1951 to 1985. I am writing this in 2012. Is it still possible to imagine that Technic Civilization lies in our future so that Ythri exists now and will be visited by a ship of the Grand Survey in 2150? Not really. If the events of the Technic History were due to occur on schedule, then they would not have been preceded by accounts of these same events presented as fiction in the twentieth century! Secondly, the future has never turned out in detail to be like what anyone had imagined, although Wells did a good job of predicting World Wars waged with aircraft. Thirdly, Anderson's faster-than-light, interstellar, multi-species trade and imperialism are particularly implausible. The series is an elaborate fiction fantastically reflecting past history partly by imaginatively projecting it onto a vaster spatiotemporal scale while however also incorporating serious scientific speculation about extra-solar planetary environments:

there might be planets like the industrially valuable Satan and Mirkheim even if no interstellar civilization ever exploits them;
there might be planets like Ythri and Avalon even if not inhabited or colonized by intelligent ornithoids.

To return to appreciating the series as fiction, the founding of the Avalonian colony by Falkayn was occasioned by the decline of the Polesotechnic League and the founding of the Terran Empire by Manuel I was occasioned by the collapse of the League's political counterpart, the Solar Commonwealth. Then, colony and Empire fought. Thus again, Anderson wrote not a single one-dimensional narrative but several skillfully interwoven series.