My campaign has very dangerous areas, but also relatively settled ones. Even with magic provided by helpful druids and nature clerics, there has to be a lot of farmland per person to sustain a society. If settlements are being constantly raided, civilization will collapse.
Halfling farm settlements are in the more settled areas. Occasionally they are overrun, just like every other race. On the other hand if you have a choice of raiding a village that has more food per individual, more wealth, are just as easy or easier to raid or a halfling village where the inhabitants need half the food per person, don't have much in the way of material wealth and are just as dangerous or even more dangerous which one are you going to raid? You can't even loot weapons or goods from a halfling village - they're all sized for small individuals.
EDIT: Halflings are also quite willing to simply melt away before enemies and become nomads like their cousins.
Halfling farm settlements are in the more settled areas. Occasionally they are overrun, just like every other race. On the other hand if you have a choice of raiding a village that has more food per individual, more wealth, are just as easy or easier to raid or a halfling village where the inhabitants need half the food per person, don't have much in the way of material wealth and are just as dangerous or even more dangerous which one are you going to raid? You can't even loot weapons or goods from a halfling village - they're all sized for small individuals.
EDIT: Halflings are also quite willing to simply melt away before enemies and become nomads like their cousins.