We learn the names of three Nyanzan nations:
Rossala, which is ruled by a Sheikh.
Uhunhu is a million-year old ruined sunken pre-human city of dolmens and menhirs, used as a base by A'u, a fifteen-meter-long, whale-mouthed, talon-legged amphibian with hands on boneless arms who, like Aycharaych, is not Merseian but serves Merseia and has fought Flandry before although "The Game of Glory" is the only story featuring this particular adversary.
Flandry first meets Aycharaych between chasing A'u out of Spica and catching him on Nyanza. Aycharaych later tells Flandry that his side will miss A'u. We are to understand that Flandry and Aycharaych have clashed between their first meeting and the occasion when the latter mentions A'u. However, we read of Flandry-Aycharaych encounters only in "Honorable Enemies" (the first meeting), "Hunters of the Sky Cave" (mention of A'u) and A Knight Of Ghosts And Shadows (the last meeting). Despite his massive output, Anderson was a restrained author who never overdid anything and later launched new series instead of merely rehashing the Technic History.
In the Kith History, human colonists of a planet with a large ocean became aquatic. Maybe some Nyanzans will do likewise?