Kirin are the mythological empowered species of Syneese, the Greater Goddess of Air. They are seen so rarely as to be considered fables, but there is enough overlapping evidence that I am certain they exist. They look something like a large goat with an impressive flowing mane and impressive gnarled horns. Incredibly intelligent, powerful, and generally benevolent, most recorded interactions with these creatures have been positive. However, they are also just as mischevious as Syneese, and so have been known to prank hapless humans.
Kirin spottings only appear to happen on high peaks where the air is thin, ironically. Perhaps because they embody air, they take much of it from around them. Either way, I speculate that this is the likely habitat of these creatures.
Although Kirin have much similarity to goats in appearance, they are reported to project immense intelligence and power - there is no way to mistake one for a common goat. Not to forget that they are usually found flying despite having no wings or clear form locomotion, which I daresay would be extremely unlikely to see happening to a goat!
Their connection to Syneese gives them some sort of air-based magical capability, but it's not known exactly what it's called or what its limits are.
Kirin are known to be prolific shapeshifters, often using different forms to perform mischief.
Little is known about Kirin history. Several human kings and heroes have reported encountering Kirin and profiting from the experience - granted power, health, or other boons. The priests of Holy Vess report seeing them frequently, and as such they are a part of their godly worship.
Throughout history, they don't appear to have occurred more or less than in the past. That is - there are rare encounters periodically, and those are generally with benevolent and good humans.