"place them where you want", they said. But if you want a consistent world, not every placement will make equal sense. Find thoughts and inspiration on where (and why) to put the Raven's purge sites.
Beware:
Spoilers ahead
Although your GM might have an entirely different view on the world. You have been warned, though.
Vale of the dead
The Vale of the dead is very secluded and hard to find (unless you follow the evil eye) The game itself suggests that you can place the stanengist crown here and having Scrome watch over it is only second to hiding it in the stillmist.V45 or its neighbours are suitably hard to reach. If you feel that's too close to Rustland (Harga/Begrand) and in reach of cunning demons, move it towards Y50.