The Song of Woe is the apocalypse that makes this a post-apocalyptic campaign. This page relates the history of the Song and its aftermath. For effects on magic, click here.
Once there were a people. It is known that they were a distinct, demi-human race, but their exact identity has been lost to time, since they are all dead. In fact, it is thought that the collective forgetting of this race was one of the effects of what they did.
The race (now called the People of Woe) had a long history of servitude. Some situations were better than others (the difference between being a slave in the mines and a slave in the house of a king), but all the People of Woe were slaves, on way or another.
After millennia of this treatment, the People were tired. Tired of being slaves, tired of having their offspring ripped away from them for the convenience of their owners, tired of working all their (usually short) lives for nothing. Tired of all of it. One day, one of them, far from Sacawisha, began to express his exhaustion: he (she? no one really knows) began to sing.
Others of the People took up the song. For several years, the People sang to themselves. Others noticed the song, but dismissed the singing of slaves. What no one realized was that the People were communicating with each other, by song, across the continent. And what they were communicating, and discussing, was a plan for a suicide pact on a grand scale.
It turned out that the People of Woe had a few tricks up their sleeves, knowledge painfully gained over several thousand years. They knew a secret: there were songs which would act directly on the fabric of magic, the little understood connections between the Prime Material Plane and the Positive and Negative Energy Planes. By singing, then, they could cast a magic spell. By all singing at once, they could cast it on an unimaginable scale. Their treatment at the hands of humanity guaranteed that the song would be a dark one.
So it came to pass. After years of debate and discussion, the People of Woe decided to go ahead and die. One day, they all (all!) began to sing. It was the same song, at the same time, across ten thousand miles.
The vast majority of human and demi-human races were susceptible to the Song of Woe. Of the people (humans, elves, halflings, gnomes, etc.) within fifty miles of any of the People of Woe, seventy percent died immediately. A further twenty percent or so went permanently insane. This left only ten percent or less of the pre-Song population to carry on—and further trials awaited them.
The People of Woe died as a result of their efforts. They did leave behind a reminder, though. Each of the People of Woe turned into a Song Zone. The more People there were together, the bigger the Song Zone. If a Zone was big enough, an Inner Zone would form, spreading madness to all who were within it (the animals and people who were driven mad were, and are, called the Mindlost). The effects of Song Zones are discussed further in the page on magic.
Magic itself was badly disrupted by the Song. For over fifty years, simply casting a magic spell was an invitation to madness, as the Song reverberated through time. High- level magic was completely lost.
So, that surviving ten percent had to deal with Song Zones that would drive them mad; the Mindlost, who wanted to kill and then kill some more; rotting bodies everywhere; disease everywhere, as a result of the rotting bodies—and they didn't have the use of magic to help them cope.
The next century was pretty rough.