The teaser in the very first episode planned for airing will deal with
the similarity between Centauri and Humans...down the road, we will be seeing
more of Londo, and his people, and realize that they aren't as human looking
as they first appear. There's more there.
It was Minbari Federation, Centauri Republic, Narn Regime, Vorlon Empire
and Earth Alliance, for anyone keeping track. And yes, most all of them have
some other alien species within their sphere of direct influence.