Upon the Divine Bridge.
The sixth Dao Realm was the Formless Realm, with a lifespan of up to nine thousand years.
When the spirit was refined to merge with color, one was called a Perfected Person; once the spirit had become numinous, color and form were no longer fixed. They transformed according to circumstance and manifested in response to things, hence the name Formless!
The simplest way to understand it...
Formless Realm cultivators had already become the highest, ultimate, perfect Perfected Persons—the final great realm before immortality.
They were not bound by the existence of a physical body, nor by the forms of flowers, birds, fish, and insects, nor by the outward appearances of men, women, young, or old. Instead, they manifested different forms according to their surroundings and intentions;
I was "nowhere at all," yet also "everywhere." I was nonexistence and existence alike, possessing boundless divine abilities and magical power!
Thus, if one chanted my name, I would know. Not even time and space could stand in the way.
The Soaring Serpent, Four-Eyed Giant, and other powerful beings that had descended upon the Red Flame Domain had reached this realm.
If they wished, they could transform their colossal bodies at any time, changing into humans or creatures of any other race. They simply did not wish to do so.
Moreover, even without relying on the Forbidden Land, they could descend upon other withered worlds through their own strength.
Had Shen Mo called out their true names while still in the Primordial World, no matter how far apart they were, such beings would have sensed it. It was much like how the heretical True Lord Lin Zhaozai could sense in the unseen that Shen Mo was about to erect the Divine Bridge after making a Dao oath. As for whether