Assassin’s Creed Valhalla (ACV) has 19 Raid Locations. This guide contains a map that shows the location of all Raids.
Raids allow you to pillage enemy camps that contain Supplies and Raw Materials. You need these materials to create new buildings at your settlement Ravensthorpe. By default they are hidden behind a fog on the map. Knowing where they are comes in handy when you want to upgrade your settlement’s level with more buildings.
You can do them at any time after doing the first story-related Raid in England. However, most are in high level areas and are better saved for later. Everything can still be done after the story in free roam. The way Raids work is that you drive by a Raid area with your ship and then activate the Raid via the displayed on-screen button when being close enough. Alternatively, you can also go there on foot and select the Raid option from the item wheel (hold Dpad Down).
Raids are marked with a red axe icon on the below map: .
That’s all 19 Raids in AC Valhalla. Also remember you can find additional cargo at Wealth locations (marked gold on map) which provides additional materials for building your settlement.