The Divine Kingdom was very big, so Song Shuhang could not directly transfer it into his 'Inner World'.
Moreover, the fragments of the Heavenly City were only a small part of the Divine Kingdom, so they would need to be separated from the rest before getting moved into the Inner World.
Song Shuhang only needed the fragments of the ancient Heavenly City. As for the other parts of the Divine Kingdom that were filled with the 'hateful' energy of the flaming eye, he didn't want to bring those into his Inner World.
In the past, when he'd transferred the various fragments into his Inner World, he'd always been assisted by Senior White Two or some other senior.
Song Shuhang thought to himself, Should I ask for Senior White Two's help again?