I got the idea for Arrival of the Gods some ten years ago after reading James Clavell's Shogun.
The plot is the following: a Dutch merchant ship defies the Portuguese and Spanish superpowers and finds a way to Japan - at a time when nobody knew exactly where Japan was. The ship crashes on Japan's coast and the surviving crew is taken captive. John Blackthorne, the ship's pilot, is our eye into the Jesuit's struggle to influence Japanese politics in order to gain a trading advantage.
While Europe had been busy building ships which could cross the oceans and push back the edges of the map, 17th century Japan had been isolated for centuries. On the battlefield, its puny navy and lack of firearms made it a weak opponent, but Japanese society was organised, efficient and its inhabitants were way more numerous than any European nation.
Japan would have lost any battle the European nations might have brought to its shores, but the cost of landing an invasion force large enough to be a real threat was prohibitive and Europe couldn't use their divide and conquer approach with such a culturally-compact people.
Yet, despite all of this, despite being at the mercy of cannon-carrying caravels, despite its technology being far inferior to Europe's, Japan considered itself superior, more civilised and more refined.
While Shogun is probably the peak of Clavell's storytelling, what struck me the most was the rich tapestry against which this story was set. I was especially fascinated by the point of view of the Japanese. What would a society which considered itself superior in all ways think of a technologically more advanced enemy it couldn't beat?
All I could think about was: could I tell a similar story from the point of view of the weaker power?
I tried looking for another period in history where such a story would be possible, but I couldn't find one where the stronger force was kept in check by the weaker one. I have to admit I probably didn't do a great job in my research - there must be dozens of examples where geography leveled the playing field -, but I also realised another thing: going the historical way would require an incredible amount of research, while all I wanted to do was to tell a story.
But if I couldn't look back for inspiration, I could definitely look forward.
I've been reading science-fiction since I was a kid: Dune and Foundation being among my earliest favourites. Then I discovered Neuromancer and I fell in love with Gibson's prose. But it's the more recent wave of hard sci-fi like The Martian, The Expanse and Seveneves which has rekindled the passion and convinced me that this was the only genre which could support the story I wanted to tell.