Eddison's Zimianvian dates are all reckoned anno Zayanae conditiae, from the founding of the city of Zayana. In these terms, Mistress of Mistresses covers a period of two years beginning on April 22 of the year 777 A.Z.C., ten months after the death by poison of the great King Mezentius[...].
The question of the relation between Earth and Zimiamvia led to the writing of the middle book of the trilogy, "A Fish Dinner in Memison"; this book, in its Zimiamvian portion, covers a period of five weeks in the year 773 A.Z.C., and ends nearly a year before the death of Mezentius (and hence approximately a year and a half before Mistress of Mistresses begins).[...]
But there is still a further question: "whether what took place at that singular party may not have had yet vaster and more cosmic reactions, quite overshadowing those affecting the fate of this planet" It is this question, together with the (strangely related) problem of how and why King Mezentius came to die at the height of his powers, which led to the writing of The Mezentian Gate. This final (or initial) book of the trilogy covers a period of some seventy-two years (702-776 A.Z.C.) beginning twenty years before the birth of Mezentius and ending with his death.[...]