Found them. Underground cities built into mountain ranges. There are dozens but there are seven large ones, with populations from five to twenty million. 

"Well there's millions of 'em isn't that grand."

"And I'm not even confident 'convince them to evacuate' works, since if the Enemy slips one agent in with them he can destroy wherever you send them and we can't verify non-Enemy status with oaths.

Well.

We could make them all swear oaths on the assumption the Enemy agent actually wouldn't be able to do it."

"If Dwarves can do that. They don't back up. The orcs also mentioned Men."

"I've been assuming Dwarf oaths don't do anything. But shapechanger Maia posing as a Dwarf oaths do something, so we can still weed them out. Men? Have you checked out all their written works?"

"Not yet!"

What've we got?

An astoundingly slim set of stuff. All from the last three weeks. Most of it is literacy exercises.

"Well, apparently they are new to the concept of writing."

"Oh," he says. "They're probably new altogether. Eru drops new species on this planet sometimes."

"What a brilliantly responsible choice of moment in history."

"Where are they and is there anything we can productively do about them?"

Maps published in the last three weeks?

There are some orcish ones, designating a land east of them as the birthplace of Men.

"They're over there and it seems like they've mostly been talking to orcs."

"Trying to say hi might just get them caught in the crossfire. But I can't help but expect the orcs will push their religion."

"This has occurred to me too. You know it almost sounds like a harmless community bonding sort of thing except for the fucking oaths and the literal existent deity who lives up north and desires mayhem and death."

"If Men are new to the planet they probably got introduced to writing by the orcs. Is it the same alphabet?"

"No, actually."

"I kind of want to put all these puzzles up on our internal message boards for people to think of things I haven't thought of but we have not in fact invented encryption and should probably assume the Enemy can read those."

"Don't know if I should consider encryption an escalating tech," Cam sighs.

"At the ceasefire I can propose to the Enemy that we all fight with swords and bows, see how that goes over."

"Oh, no, not bows, the horror, atlatls."

"Clubs and thrown rocks?"

"Stern looks and rude gestures."

"That was how we warred in Valinor! And then the stakes changed and we realized we didn't have the 'de-escalating' skill more militant cultures must acquire. Valinor had a violent crime rate of 'what's that'."