I turned up in Beluaterra a good while after the Second Invasion I think. That was the last invasion not to have RP driven hordes. I think a heck of a lot of realms and regions were driven rogue and a lot of damage was done to Beluaterra though. Utterly ravaged populations and what have you, whilst we were also labouring under a different tax and hierarchy system back then. Talk persisted for ages of how realms were still recovering from invasion six months or so after I arrived. It was inhibiting war across the continent. The lingering debilitating effects actually delayed the imposition of the Third Invasion a lot longer than it was supposed to I believe.
The aftermath of the Third Invasion was different. There were a fair few rogue and daimon held regions dotted about, but most surviving realms were generally territorially intact and their economies were not completely ruined and/or eradicated. So yes, there was some damage to everyone, but not as painful as you might think. Food was an issue at the time. I can't really tell you whether hordes still roamed or what have you. I quickly cleared off to Wudenkin to help the newly established Valhus feed itself. I was just trading.
The Third Invasion sort of ended with a whimper rather than a bang you see. One minute it was invasion, the next it wasn't. A few realms worked together then to destroy the last vestiges of Arcane's realm, Vlaanderen. There was discussion here and there about what to do about a few surviving daimonic enclaves. I think Heen, Sint, Mesh and perhaps Old Grehk briefly teamed together to try to tackle the lands north of Sint but they were never recovered. Then Mesh made it her duty to quest all over to destroy surviving daimonic enclaves although she'd made it round most rather than all of them by the time the Fourth Invasion finally rolled round...
