Zhou Tian had to retrieve the Ancient Ruins Space back to the Main Plane in the past, not because he couldn't make those territories his without bringing the Ancient Ruins Space to the Main Plane. In fact, Zhou Tian only needed to send a certain number of Beastman to guard those ancient Ruins Spaces he had occupied. Even without returning to the Main Plane, the Ancient Ruin Spaces he conquered would still count as his territory.
However...
