The River of Time was merely the River of Time, not the true Time Great Dao.
Otherwise, never mind entering the River of Time—a Profound Immortal could not even sense its existence.
The River of Time was a river born from a sliver of the Time Great Dao's source.
It existed because the world needed a River of Time.
The River of Time in a Grand Cosmos was born from the origin of the Time Great Dao.
The Rivers of Time in Lesser Worlds and Greater Worlds, meanwhile, were born from the origin of the Time Law.
Of course, since it was born from the Time Great Dao's source, never mind Profound Immortals—even Daluo Golden Immortals could not touch a Great Dao source before attaining enlightenment of the Dao.
Then why could Profound Immortals sense the Primordial World's River of Time, and even enter it?
That came down to the cultivation system.
Under its established rules, Profound Immortals of the Primordial World Origin Immortal Dao system could sense the Primordial World's River of Time and briefly enter it.
It was much like an authority.
Reaching the Profound Immortal realm was equivalent to gaining the authority to sense and enter the Primordial Wilderness's River of Time.
If a Profound Immortal from the Primordial World traveled to another Grand Cosmos, they would not possess that authority. Without permission, they naturally could not sense that Grand Cosmos's River of Time, much less enter it.
The saying that different paths of the Great Dao led to the same destination meant just that. To touch a source Great Dao, one had to be a twenty-sixth-tier Daluo Golden Immortal.
Profound Immortals were only at the seventeenth tier. They could sense and enter the River of Time solely because their cultivation system granted them that permission, nothing