Yes. As you kill each Boss the raids begin from the minions of the next one.

With the advent of the most recent Boss they have limited the raids on the starter Biome so you'll always have a base are that never gets the hardest raids.

On top of that you can trigger raids but specific creatures if you kill enough of them . For example hunt enough Trolls and you may get raided by them in revenge. etc

Overall its not bad and a thing they are actively balancing as we go. The initial release of the top most Bosses Minions was considered by many pretty brutal so they dialled it back after only a few weeks live.