The two Demons worked together to send Thirty-seven back inside the separate dimension at that point.
They couldn't control the automaton, but the fact that it was losing energy, coupled with a few promises, convinced him to return to the Hive.
Thirty-seven could travel through the dimension freely since he had set its structure, and he wasn't affected by its length like ordinary cultivators.
He could just travel from side to side in a matter of hours since he could directly fuse with its fabric.
That greatly helped in setting exits in strategic points since Chasing Demon couldn't just leave the headquarters of the Hive.
Flying Demon had to learn how to create entrances and exits in the years spent inside the tunnel, but it didn't take him much to achieve that with the help of the automaton.
Yet, in the end, the Hive obtained a tunnel that connected the desert in the southwestern coast with the Coral archipelago and the Udye mansion.