A keen is an instrument invented by ogres sometime after they migrated from the Drop Lake Mountains to the Kimrin Mountains. There is no record of precisely when it was invented, though it is thought to be late in the seventh century or early in the eighth. However, oral tradition among ogres (who did not begin keeping written records at all until the early tenth century), the inventor was named Yuli, who was apparently also a spirit-talker. It's said that Yuli believed ogres should have music, just like humans, and learned from spirits how to make some of the instruments which existed among human society on The Land (though ogres at that time had no contact with humans). But Yuli also thought that ogres should not limit themselves to human instruments, but should invent instruments of their own. In fact, he was hoping he might invent something which not only bore little or no resemblance to other Landian instruments, but also little or no resemblance to any Terran instruments. When he was finished, he asked a spirit if what he had created was truly unique. According to the story, the spirit said it wasn't quite like anything she'd seen or heard before, but reminded her somewhat of a cross between a bullroarer, a didgeridoo, and a caxixi. Keens are played by shaking, spinning, or swinging the instrument. It is both a percussion and wind instrument. One who plays a keen is called a "keener."
Also according to the story, an ogre friend of Yuli's (whose name is not mentioned in the oral tradition) is credited with giving the instrument its name. When Yuli first demonstrated the instrument for his friends, he said he hadn't thought of a name for it yet. After listening to him play it, one of his friends said, "Whatever it is, it sounds keen."
It is also said that after inventing the keen, Yuli resumed his efforts to invent something so unique that even spirits wouldn't be able to compare it to anything. Ogres say that he eventually succeeded, though they will not share the name of the new instrument with humans, nor has any human seen or heard whatever it is. It is considered the property of ogre culture, and will not be shared with any other race. There are those humans who have expressed skepticism over whether such a thing truly exists, considering the fact that it is known that on Earth there are many thousands of types of musical instrument, and it seems unlikely that Terrans could have overlooked any possible means of producing music.