User blog comment:Supahbadmarine/By Tzeentch! Here We Go!/@comment-2253300-20130212214731/@comment-4608429-20130212223048

A Sector is a masive space, Legion, and you could even say that the Emperor gave each of a different recording to give them different, but complementary views. But your not entirely wrong, as their raised by scientists, not the individual societies of each planet.