The Tide Of Empire

"Dwelling north of the Wall, the Votadini had formerly been subjects and, after the tide of empire moved southward, had stayed on reasonably good terms."

-Poul and Karen Anderson, Roma Mater (London, 1989), I, 1, pp. 19-20.

"Tonight Irumclaw lay like a piece of wreckage at the edge of the receding tide of empire. What mansions were not standing hollow had become the property of oafs, and showed it."

-Poul Anderson, A Circus of Hells IN Anderson, Young Flandry (Riverdale, NY, 2010), pp. 193-365 AT CHAPTER TWO, p. 204.

These passages confirm that Gaius Valerius Gratillonius and Dominic Flandry live in similar periods albeit in the past and future respectively of alternative timelines.

We have become familiar with:

the Time Patrol timeline in which Sherlock Holmes is a real person;

the King of Ys timeline, inhabited by Gratillonius, in which various deities are real beings;

the Technic History timeline in which the Terran Empire recedes from all but the treaty port boundaries on Irumclaw.