An Intermediate Period

Sandra Miesel's Chronology of Technic Civilization tells us that, in the twenty-third century:

the Polesotechnic League is founded;
the planet Aeneas is colonized;
the planet Altai is colonized -

- and that the third installment of Poul Anderson's Technic History, "The Problem of Pain," is set in the twenty-fourth century.

Of the three events that Miesel locates in the twenty-third century, the only one that directly impacts "The Problem of Pain" is the colonization of Aeneas. In "The Problem of Pain," the University of Nova Roma on Aeneas attracts extra-planetary students, including Ythrians, whose planet had been discovered during the Grand Survey in the second story, "Wings of Victory."

The League is not mentioned until the chronologically overlapping four and fifth stories, "Margin of Profit," introducing Nicholas van Rijn, and "How To Be Ethnic In One Easy Lesson," introducing Adzel. Altai is not mentioned until the tenth story (the third about van Rijn), "Esau." Of course, the League must have been founded and Altai colonized much earlier than these first appearances. Nevertheless, since the League is mentioned nowhere in "The Problem of Pain," I do not think of this story as belonging to the Polesotechnic League period of the Technic History. Instead, it is in an intermediate period when the Ythrians, having acquired hyperspace travel from human beings, are learning, e.g., by attending Nova Roma University, and exploring, e.g., in this story, the planet that will later be named Avalon.

Thus, these first five stories introduce Jerusalem Catholicism, Ythri, Avalon, Aeneas, the League, van Rijn and Adzel, and the sixth introduces Falkayn, all important later.