The real reasons of the shapeshifters' warmongering are lost in history; whether they wanted to rebuild afterwards, simply sought destruction, or followed some other plot, is unknown.
"It's not that we think our men were worth any less than us. It's that we don't trust them - after the cruelties committed by them in the Splinter War, they have no business being around weapons."After the war, the maps had to be redrawn. Shapeshifters were hunted and killed, shapeshifting was outlawed. Natural shifters were presumed extinct, spells forbidden, the name used as an insult.
— Kiromatonak Stillhand, Brighthold scribe
Two millenia later, the shapeshifters' role in society was rediscovered, along with the forgotten spells. Scientists made a great effort for its acceptance and today, very slowly, shapeshifting is growing back into society.
"You should overcome the Splinter War. Even if it was such a great incision, you cannot linger on it forever - how will you brighten the future if the past throws such shadows?"Artists' notes
— The Kirnanas fleeter
The original German "Splitterkrieg" might be more accurately translated as "Shatter War" but I didn't like how it sounds.
The Splinter War is a deep cut in history - there's a before and an after, and both are very different. So much was destroyed that entire countries have been forgotten. The war and the difference to before will be interesting along the way of telling the story of Genius Loci.
Why, do you ask, have the Four not helped? Because the Splinter War started at the end of one cycle and prevented the new one from beginning. The Years of Sorrow were not four years that time, but decades of a world without the Four to protect it from itself.