Historical Time And Time Travel

My favourite two themes in sf are time travel and future histories. Amazingly, Poul Anderson wrote both the Time Patrol series and the History of Technic Civilization.

A future history is about the passage of time for societies and civilizations whereas time travel is about the fascinating idea that we might first study a historical period, then experience it, as Carl Farness does in "The Sorrow of Odin the Goth."

Later instalments of a future history series build on and add to earlier instalments. For how Methuselah's Children does this in Robert Heinlein's Future History, see here. Poul Anderson's A Knight Of Ghosts And Shadows builds on:

the Taurian Sector;
Merseia;
Ythri;
Avalon;
Esperance;
Diomedes;
Nicholas van Rijn;
the Falkayn name;
Persis d'Io;
Chunderban Desai;
the McCormac Rebellion;
Aeneas;
Talwin;
Aycharaych;
Chereion -

- and adds:

Dennitza;
the Molitor dynasty.

Thus, A Knight... is firmly based in a complex history and also significantly advances that history, as do subsequent volumes.