Goblins have lived in the high Southern Alps for about as long as any other people has walked the earth. They call themselves the Ninchiti in their own language, which roughly means "those who soar".
And soar is what they do. Life in an extreme environment brings about extreme solutions, and though nobody can nowadays remember the enterprising Ninchit who dreamt up the Soaring Frame, what's for sure is that he (or she) came up with the most extreme solution to the most extreme problem of all - how to get around when you spend most of your life in caves burrowed into sheer cliff faces, often 5000 metres or more above sea level.
The Soaring Frame is an elegantly simple design - a plain crossbar of hollowed-out yak bone, across which is stretched a thin strong material, usually yak skin but sometimes that of dead Ninchiti (being asked to provide a skin for your ancestors is considered a great honour) or their enemies. This creates a kind of loose, flexible square parachute, from the four corners of which pieces of flex (often sinew) hang down. A skilled Ninchit can manipulate the frame with astonishing subtlety and dexterity, by pulling on these pieces of flex and guiding his or her flight.
Nevertheless, the Soaring Frame is a highly dangerous vehicle. Flights result in death or injury fairly frequently. Usually this is in take-off and landing - which involve sprinting down a cave tunnel and leaping out into the abyss, and then trying to guide yourself into a tiny cave mouth without hitting the cliff face on either side. Nevertheless, the alternative - climbing out from a cave down a sheer wall of rock for hundreds of metres, then traveling by foot across a wild valley bottom, before climbing up another cliff face to enter the other cave - is no comparison in terms of ease, speed and safety.
The only problem with the Soaring Frame is that pretty generally it can only glide downwards - because it has no form of propulsion other than gravity. This means that often it can only be used to travel from a higher cave to a lower one on the opposite side of a ravine or valley - although the existence of vortices and upward air flows can make it possible to lift altitude temporarily. It is also vulnerable to the wind, so on blustery days the Ninchiti use their Soaring Frames like parachutes to glide down to the valley bottoms - much safer than attempting cave-cave flight.
Soaring Frames are Class D flyers. Goblins cannot perform attacks while piloting one - its use is as a form of transportation alone. A tactic often used when the Ninchit spot travelers moving through mountain passes is to swoop down from caves in the cliffs above, landing close by and taking their victims by surprise.
The Ninchiti's commonest foes are the Aarakocra, as they often come into conflict over cave systems - which are after all finite in number. They also sometimes tangle with the Dwarven clans who inhabit the foothills of the Southern Alps.