One hundred and twenty years ago, disaster engulfed the world. It was first sighted off the eastern coast of the Ninefold Celestial Empire, a crimson fog and waves lapping red as blood against the shore. The fog crept inland to cover seaside villages and cities, and the scattered reports of survivors spoke only of the demons dwelling within the hateful mist. Within weeks, the Red Tide had encircled the whole of the Empire, and the red fog had rolled to cover the land. The only survivors were those few fortunate souls who had been able to take ship before the tide overwhelmed them.
Similar scenes played out across the globe as the peaceful seas turned gory and innocent fog was wetted with the blood of the slain. No sorcery seemed capable of holding back the fog for long, and even the greatest heroes were eventually dragged under by the sheer unrelenting numbers of the demons. Men and women fled vainly in their ships, seeking some land that had not yet been consumed by the infernal vapor.
The Sunset Isles were in one of the far corners of the world, an isolated chain of islands of no special worth to draw the interest of empires. Yet here and here alone the Red Tide drew back, and here alone sanctuary was found for those few refugee convoys fortunate enough to land here. The waters turned to blood a hundred miles offshore, but closer the waters remained clean, and only sneaking tendrils of fog dared roll in to threaten shoreside villages.
The Isles were not uninhabited, of course. A vast patchwork of warring goblinoid tribes covered most of the isles, engaged in desultory warfare with the wary remnants of a dwarven colony established in ages past. A few hermit-villages of philosophical elves could be found ashore, and several stout human statelets born of abortive colonization efforts or shipwrecked crews. Other humanoids and stranger things lurked around the edges of the isles, and murmured rumors of old gods could be heard in village alehouses late at night.
The refugees had absolutely no interest in the claims of the goblinoids. Doom was at their back and their wives and children faced lingering death should they prove unable to cut a foothold into the goblin lands. The refugees struck the warring tribes like a thunderbolt, their heroes and mighty wizards blasting whole tribes into oblivion and raising new towns in which to house their kinfolk.
The goblinoids were forced back into the corners of hill and plain, and up into the heights of the mountains. Disorganized as they were, they could not unite in the face of such desperate resolve, and were reduced to raiding and slow, constant warfare against the interloping refugees. The newcomers were resigned to their lot, as facing goblin warriors was far more appealing than turning back into the Red Tide.
In the decades since, small villages have grown steadily and towns have become modest cities. The initial unity among the refugees has fractured as their interests diverged, and the goblinoids in the mountains grow more convinced of the threat posed by the intruders. Few expect that the current "peace" will last much longer. And all the while, the Red Tide still churns far offshore, sending fog and dreams to the islands to tempt weak-willed servants into obedience.