Originally Posted by
Shoebopp
In order to actually raid a tile, it must be considered farmland. You can check if that tile is farmland by holding down right click while your mouse is hovering over it. It should show "low fertility", "medium fertility", or "high fertility" in order for the tile to be devastated and thus enable raiding. Since you're playing as Saka, a lot of nearby lands are infertile steppes, which is probably why camping a general in those lands isn't causing any raiding
Edit: as you've mentioned, the "southern settled lands" can be raided simply because they have a ton of "x fertility" tiles