There is also a lack of gunpowder in the periods fantasy draws from. For Europe, the "mythical age", the hazy area where all things start which, at least feels pre historical, is the middle ages. The modern nations trace their semi mythical and fantastical origins to that period: your average French person would probably list Charlemagne as the First King and founder of France, English would probably be tempted to say King Author. At the very least, in the collective myth of those countries, those two probably have a bigger impact on the collective imagination of what those countries are and came about than any actual history of it.
King Aurthur I think helps show that European myth has been framed in a medieval context for, well, a thousand years starting in the high middle ages, and certainly from the beginning of the modern period, with Le Morte d'Arthur being published in the 1485. I guess this does somewhat depend if one considers the modern era to more begin with the Reformation or the Enlightenment in the 1700s or the Reformation in the 1500s.
But, as we can see with the story of King Authur, the medieval period has long had a very large place in the imagination of Western People as a mythic, legendary age, far predating Tolkien. Medieval fantasy dates back to, well, the late medieval, with 1100s works like Beowoulf and Historia Regum Britanniae talking about mythical events occurring allegedly in the 600s.
So, medieval fantasy is a 1,000 year tradition, which most works, including Tolkien are building on. It makes sense that people would continue to set their fantasy in an age (500-1300 AD more or less) as follows tradition.
The other big mythical/legendary age of course is the Homeric tradition, which was the Roman/Greece mythical/legendary pre history where those writers continually set the Classical era's Fantasy stories, where gods, beasts, and Heros casually walked the earth. Its no accident that if a fantasy story is not set in a medieval setting, its set in a Homeric setting, though we tend to mix and match Greek, Egyptian, and other early iron to bronze, or pre-bronze civilization.
I think we put too much weight on the social political effects of guns, and the weight of Tolkien as well, and under weighs the 1,000 year tradition of Medieval fantasy, and the nearly 3,000 year tradition of classical Mediterranean fantasy.
Guns in part simple came after the ages that the fantasy genera are traditionally set in. Writings that include guns, simply by when they were written, are post the fantasy era, and are very modern. And even in those works, the earliest I'm aware of it Don Quixote, the middle ages and civalry loom large in the imagination: as much as its mocked in that book, its often mocked from a position of deep love and its seen as something almost tragic that tilting at windmills is the closest a man can get to medieval ideals.
military-fantasy.com
