The Peloran created us.  Most of us still are Peloran.  But we have spread out over the millennia.  The Arnam of course.  Joining the Terran and later the Aesiran was seen as risky though.  Neither race has the gene-deep devotion to rules that the soldiers of the Albion had.  We knew they would question the rules, and in the end they broke the rules.  And in our never-ending quest to be more human, we emulated them.  We really are Terran and Aesiran now.