The XXX is part of a what series?
The Virgin of Zesh
As dated in the 1959 version of de Camp's essay ``The Krishna Stories'' and James Cambias's GURPS Planet Krishna (a 1997 gaming guide to the Viagens series authorized by de Camp), the action of The Virgin of Zesh takes place in A.D. 2150, falling between The Prisoner of Zhamanak and The Bones of Zora, and making it the ninth story set on Krishna in terms of internal chronology.