The Long Silver Night referrs to the century from 1574TD to 1674TD in Karsunt. This century, also known as the false apocalypse, Tim-hurr'tè did not return with the sun one morning, and the night did not end. In time most of Karsunt was covered in encroaching ice, until a powerful conclave of wizards managed to temporarily shift the diskworlds climate back to more favorable conditions. Of course, without Tim-hurr'tè present, the glaciers could do little to kill the inhabitants of the world, who simply remained alive, even if frozen in place, or burried under tons of ice and rock. In time the people adapted, the humans especially, and as the century progressed, they realized the only ones vulnerable to death, or something akin to it were the undead, who could still be destroyed, so people set out, forming war parties, and raiding vampire and necromancer strongholds, purging all undead creatures to the best of their abilities.
When the century had passed, and Tim-hurr'tè returned wearily, putting the sun back where it belonged, three of the four great vampire houses, McDougal, Dracula, and Riedengrass had been practically destroyed, hanging only by the loose threads unwittingly left behind in the wake of the genocide. Only house Yamamoto remained relatively untouched, as their doings had been more covert, and their base of opperation widely unknown.