[Mediterraneo10]

It's the same thing. If we’re going to laud Iceland for being the settlement of a terra nullius, then clearly those Irish monks had claim to it, and the subsequent settlement of the Norse without their invitation represented encroachment on someone else’s land.

[raverbashing]

"Had claim" that's naive

Trying to apply legal concepts to unclaimed barren islands not subject to any legal system does not work.

"Bigger army diplomacy" is the rule, not the exception. Weapons usually beat legal documents and concepts

[liability]

Maybe it was 'trespassing' I suppose. I don't know much about this subject but from what's been described in this thread, assuming there must have been violence seems like a leap.