It's been a really long time since I've read this series. It's a fantasy series (don't remember author or title). If I recall correctly, it's a world where there are several plot lines set.
In any case, the part I remember is that there are some invaders that rape and pillage and "Forge" the locals and afterwords they cannot remember who they are, no higher intellectual behavior, just pure instinct and savagery.
Can anyone name the series and/or author?