I realize that the narrative of the page was a bit confusing. So I've rewritten it. Thanks for bringing it to my attention, Snuffysam. Hope this is clearer.
But to answer your question, the Celestians already control the human empires. The borders of those empires only roughly correspond to the preexisting borders. So they carved up the Byzantine Empire, The Abbasid Caliphate and the Song dynasty into their own territories.
The giant alien mother ships stationed next to the human cities reminds me of a very intense Japanese manga that I could only bear to read occasionally because it was so violent, gory, and bizarre... I have forgotten its name. In this manga, dead people were resurrected with advanced technology using a laser beam that could "print" people back into existence layer by layer. These people were then forced to do battle against invisible demons, and/or super powered monsters as a form of sport. Their bald headed master controlled them from inside a big metallic sphere that he sat inside. The captured humans would wear black, strength and speed enhancing battle suits. If one of these slave warriors sustained any damage, no matter how severe, as long as they could defeat their assigned opponent, they would be teleported back to the real world and have all their wounds healed. It was eventually revealed that the bald headed guy was a German scientist who intercepted ultra advanced alien technology from outer space radio waves. He weaponized the technology and used the dead humans as guinea pigs to test it on.
Another interesting thing about this manga was that they had weapons whose destructive effects were on a delay, so that after you shot someone, they would remain unaffected for a few seconds and then blow apart!
Another interesting thing about this manga was that they had weapons whose destructive effects were on a delay, so that after you shot someone, they would remain unaffected for a few seconds and then blow apart!