As suggested, build lots of workbenches throughout your base. Workbenches deny opponents the ability to spawn within their build radius. And be sure to check on them every several days. It just takes one annoying night spawn of a Skeleton archer who slowly plinks away bow shots at your workbenches from outside your walls/moat to quietly wreck several of them, leaving you suddenly vulnerable to spawns inside your base should a full-on raid trigger. You think you are totally safe, but suddenly there is unexpectedly stuff inside your base.

Originally posted by TheGreatDruid:

You think you are totally safe, but suddenly there is unexpectedly stuff inside your base.

If that keeps happening, maybe you need to hide your workbenches in small huts. Skeletons don't attack walls.
Or just build a 20 meters high wall and make the Greydwarves pay for it.

Did you suppress the spawning with base-items like workbenches, fire etc. everywhere? If not, they will spawn wherever they can.

spawnproof your base.

with the new settings you can just turn raids off on demand.

If you have a gap in workbench coverage you can have mobs spawn inside your base. To make sure you have to walk all around your base with a workbench in your "hand" to make sure that you have 100% overlap.

Even then you can still have birds and deer spawn inside your base.
https://steamcommunity.com/sharedfiles/filedetails/?id=2920176358
https://steamcommunity.com/sharedfiles/filedetails/?id=2860289081

The next patch is supposed to have sliders/settings that will let you turn off base raids if you want.