Expedition
Fleeing the island really is foolish. The ones who didn't know this were never seen again.
Nothing helped. Ugntjas Dunl was not an illness, that could be cured. But there had to be something, so a small group of friends and family decided to escape the island. For two years they travelled around seaching for places the shield had not touched. Many people got to know them. By some they were hated, by others they were loved. When their expedition ended in failure, no one knew where to find them. They were gone.
Of course we know now where they went. Their last attempt, was to dig them selves out, and it seems they at some point gave up because the earth got to hard to dig in. They survived by using their magic and hid their tunnel to the outside world, so their enemies would not follow. Their society was discovered around 835, but up till then people had belived they had died. Intrestingly enough the effects of Ugntjas Dunl, were severly reduced underground.
Their original tunnel is long gone and we don't know where it was dug, but their society centered around Nisku, and the farthest tunnel went all the way up to Nul! In Nul we see evidence of interaction with another species, but this connection was cut off.
Today there is no longer anyone living underground. It is much easier to live above ground, but the people who lived down there still maintained, that they wouldn't become part of any other settlement, so they have their own called Loso.