My last couple of worlds wound up pretty sci-fi, including one that played a lot like I'd wound up in Starship Troopers, so I decided to generate a world in the high-fantasy style: Tech level capped at 1400 CE, seven procedurally-generated schools of magic, highly active deities. The works. Let it run up to 5k years, and had a look in legends. I was... mildly surprised, to put it lightly.
In the year 512, Urist Grimdark (I couldn't be bothered to commit his real name to memory) developed a new form of magic that allowed him to convert and enslave clowns. Two weeks later, his sister pulled the same off for Divine units. Apparently, they'd been inspired by being the last survivors of a fort that got caught in the middle of a war between the two. Something about a highly active temple site on top of a pierced candy vein. Anyway, thanks to their society's high familial loyalty trait, the two stuck together and managed to found a new empire.
It only took them about fifty years to completely dominate their world, of course. The real kicker comes in the fact that, by the year 1032, their empire had developed magitech that starts to read and function as if I'd generated a non-magic, high-tech world. It started with steam engines powered by fire-based clowns, and just kept getting worse. Now I'm sitting on a world with what functions as plasma rifles being described as the severed arms of wrath-angels shrouded in candy runes, and full-on interplanetary assault carriers carved out of the carcasses of defeated deities.
I must admit, I'm kind of impressed at the parallel development, but I was aiming for a Wheel of Time style Third Age, not another Bug War! What did I do wrong with my worldgen settings?