When your home base is raided, you may get a chance for revenge and retrieve what was lost. However, if the survivor raiding you doesn't steal items of enough value, they may not leave footprints. Some raiders are real professionals and perfectly know how to cover up their tracks. If the survivor left footprints, you can see them on the map leading to a base for you to counter-raid. The base will stay on the map for the maximum of 8 hours. 

To summon the raiders, your character must be at level 150.