I'd like to second this question. I started playing an embark-with-nothing challenge, which kind of assumes you'll eventually get things like a pick and anvil from the caravans. But it's autumn of the third year, and not a single merchant yet!
Elves and dwarves I understand -- according to the embark map we're just a little too far away from elven lands, and when I peaked into legends it turns out the dwarven civilization was extinct for decades until my seven (plus two hardcoded migrant waves) revived it. But there's tens of thousands of humans within a couple days march, and not a bloody one has felt like coming to visit. Why?!
Have you created enough wealth to trigger this in the humans entity file?
"PROGRESS_TRIGGER_PRODUCTION:1"
Oh, good suggestion, that inspired me to actually look up how those tokens are interpreted. According to the docs, that means the human caravan won't arrive until I have *exported* 500 wealth. That explains why I've never seen this before, I must have exported at least that much with the first dwarf caravan in all my previous games.
So, with no dwarf or elf caravans in this world, I guess the solution would be to arrange for the kobolds to steal a bunch of bone crafts. At least that's the only way I can think of to create exported wealth without trade. It's kind of a moot point for the fort in question, though. Here's the entirety of the fort I was able to build:
A wooden door and some bone armor couldn't save them from the weresheep.