Your base will always be under attacks, no matter where you are located. Bosses of your current biome will send their armies at you until you defeat them and unlock raids from the next boss.
Some raids will be deactivated when you defeat bosses. For example you probably already noticed that you don't have Eikthyrs and Elders armies anymore (Eikthyr rallies the creatures of the forest and The forest is moving). However, some special raids (The ground is shaking) will remain forever. Even when you reach the end and defeat all the bosses, you will still have troll events.