[astine]

a camp fire gets plenty hot for blacksmithing - just wait for the coals and then blow on them

Maybe if you're working with bronze or copper, but iron forging requires much higher temperatures than a campfire can provide. That's why the iron age took place after the bronze age, forges capable of making iron workable were not yet invented. It wasn't a trivial invention.

[bluGill]

Charcoal - which you get from campfires is hot enough. It takes a lot more of it though and a lot of other effort. when bronze is available it is generally good enough and a lot easier, but historians tell me iron was used throughout the bronze age in small amounts. iron really needs steel to be signicantly better than iron and that took a while-

[freedomben]

(I am a layman here so take this with a grain of salt) I believe you are correct, however no campfire will have enough airflow to get that hot unless you have a bellows or some other way of injecting air into it, and you'd have to have it structured in a way that it can efficiently burn the fuel. I'm not much of a blacksmith but had a friend who was into it and whose dad also was, and we did a pretty fair amount of "experimenting" as kids :-D I know from experience that elevation makes a big difference too, though I've never measured.

Would be fascinating for someone with knowledge of this to weigh in!

[bluGill]

Charcoal is great for forging, though as you say getting airflow is tricky. Still this is manageable - clay and rocks are abundant on earth so there are options.