Board Thread:Warhammer 40k General Discussion/@comment-87.194.202.186-20130622024159/@comment-7123746-20130625045347

Well, while I agree with your hypothesis that the Enslavers were probably the Immaterium's first inhabitants, I don't think they'll want that added in without a solid GW reference stating that they were, in fact, the first kids on their block. The most you could possibly say is that they are among the first KNOWN inhabitants of the Immaterium.

Hope that helps, Wikia-anon!