All named characters in Part 2 are historical. The phase of the moon on the mentioned date was computed with the program Celestia. The trippy dream sequence did happen, albeit with different imagery in our timeline, and is currently hypothesized to have been an episode of exploding head syndrome (a real neurological condition that is less icky than its name suggests). The fight on the boat also happened, although the real date is uncertain. Of course, in our timeline Descartes managed to react in time to prevent his murder. Most of my information about the flavor of this era derives from The Crisis of the 17th Century by Hugh Trevor-Roper.
All named characters in Part 3 are historical. Kristina of Sweden held, in fact, the title of King, and her incredible life is worth a hundred books. The invention of the submarine did happen as described, but its military potential was left unexplored until the 20th century. As I said, ours is the weirder timeline. The excellent North West to Hudson Bay by Thorkild Hansen provided the bulk of my information on the life of Jens Munk, and I have Felipe López to thank for tracking down that book for me. If you ever visit Bogotá, go to his bookstore Mirabilia for the best selection of science fiction to be found anywhere in Colombia. Say hi from me.
All named characters in Part 4 are historical except for Xiaobo. Her peculiar fighting style is Ground Dog Kung Fu, which was devised in the province of Fujian for the specific training of women disabled by foot binding. My data on the tradition of binding (and the no less painful practice of unbinding) came from Cinderella’s Sisters by Dorothy Ko. The man I called Emperor Zhenzui is the same man who in our timeline took the regnal name Chongzhen. My main source on the evangelization of Asia was Tras el Sueño de China by José Antonio Cervera. For information on the first diplomatic contacts between Japan and Europe, I consulted Historia de un Desencuentro by Emilio Sola and the doctoral thesis La Cruz y la Catana by Ainhoa Reyes Manzano. In 1992, the City Archive of Seville published a reprint of a chronicle written in 1862 about the diplomatic delegation that Hasekura Tsunenaga had led there two and a half centuries earlier. It’s a tiny book, but it constituted a priceless source on this tragic character. In China, Flemish missionary Ferdinand Verbiest really invented the first modern version of the steam engine as a gift to the emperor (a different emperor in our timeline), but the contraption was thought of as no more than a toy, and it never found its obvious applications. I’ll say it again: ours is the weirder timeline.
All named characters (and earthquakes) in Part 5 are historical. As I deviated more and more from events in real life, historical references started to prove less and less useful. It is true that Bartolomeu de Gusmão drew a model for an airship, but aerodynamically it made little sense. Worse still, it was based on the previous work of Francesco Lana de Terzi, who had planned to obtain buoyance by making a vacuum inside metallic spheres, a technological feat that even to us would be challenging; at least Gusmão’s more birdlike design had the advantage of not being completely impractical. The positions of the planets on the mentioned date were computed with the program Celestia. Those who wish to know more about the 1755 earthquake are advised to read This Gulf of Fire by Mark Molesky.
In Part 6, Professor Hiriyanna and his family are historical figures placed in completely different circumstances, as are Sagunabai Kshirsagar and Paulo Farnana. In real life, Professor Hiriyanna wrote numerous treatises on Indian philosophy that even the general reader will benefit from. Neema and all the other characters are fictional. The historical version of Paulo was named Paul Panda Farnana M’Fumu; whereas my timeline gives Zaire to the Portuguese, the real place was the much more dystopian Belgian Congo, and Paul’s life story is a fascinating example of what a world-class education can do for colonized peoples when unhindered by racist prejudice. Professor Hiriyanna’s friend Hariram is based on an actual printer who lived at that time, named Hariram Mishra, who ran a publishing house of certain importance in Bengaluru. Shashi Tharoor’s An Era of Darkness (known in the West as Inglorious Empire) describes a colonial India very different from the one depicted here, but it taught me much about the modus operandi of imperial oppression. His book Why I Am a Hindu provided insights that went into the crafting of adult Rukkamma’s personality. In the state of Karnataka, Mysuru (called here by its old endonym Mahisūru) is a delightful little town where the traveler gets a respite from the agitation of India’s bigger cities. Thanks again to my husband, I spent some days there in the winter of 2019 to take notes on the climate and the flow of life. In our timeline, Congolese uranium was used in the Manhattan Project.
All characters in Part 7 and the epilogue are fictional, but the highest principles of humanity are true in all possible worlds. All the tribes mentioned are historical (even if a handful of them have gone extinct in our world). I made my best effort to research their proper endonyms in order to avoid calling them by a colonial name or their neighbors’ pejorative for them. About the meaning of the United States as an ideal, Dreaming Up America by Russell Banks is a good starting point. For first-hand testimonies of the many ways the actual country has fallen short of that ideal, I recommend Extremo Occidente by Juan Carlos Castillón Martín and The Wordy Shipmates by Sarah Vowell.
All locations in the book exist in our world. The city of Munkhaven is in the same place where we have Churchill, Manitoba. We haven’t built an extranational city at the South Pole, but someone should.
Putting a historical novel together used to be infinitely harder in predigital times. The blogs Writing with Color and Mythcreants are wonderful sources on the respectful handling of multicultural settings, narratives about oppression, and wordcraft in general. A myriad of tiny tasks, like looking up the spelling of a name, untangling a royal bloodline, keeping track of simultaneous events recorded in different calendars, calculating travel distances, purging anachronistic vocabulary, describing a society’s technological state, or predicting the effects of global warming, were only possible thanks to the nearly forty million volunteer authors of the English Wikipedia. I feel like Gilberto under the dome when I consider how much I depended on the collected knowledge of humankind to finish this book.