Guns

Guns first began to appear in the underground. No one knows who they were invented by, but trade eventually made its way to the military in about 615MA. They were first seen in "public" in the hands of humans during the last major war.

To give some perspective, the gunslinger in a campaign set in 630 MA stole his first weapon, had no idea how to repair the one he had and had to rely on finding a blacksmith who was willing to tinker with it when it was broken, and generally got the response of "whoah, what is that?" from anyone who saw it.