What scales attract special units?

[Agema]

I think knights come with turmoil just like Barbarians. I think the difference is due the province type - barbarians tend to hit "uncivilised" provinces like forests and mountains, whereas knights tend to hit "civilised" provinces like farmland and plains.

Either that, or knights are the result of high order and bad luck. Even still, I'm pretty sure I've only ever had knights hit those two province types.